On Wed, 2020-09-30 at 16:25 -0400, Lyude Paul wrote: > On Tue, 2020-09-29 at 13:32 -0600, Kevin Chowski wrote: > > Thank you for the reply. And in regards to digging into it further, > > thanks for requesting that I do some more due diligence here :) > > > > Also if you did get around to it, thanks for double-checking with > > Bill! Let me know if you'd like me to reach out instead, or if > > anything else needs to be done in this regard. > > > > So to clarify the plan: if we do actually move forwards with leaving > > the current functionality as the default, do we need to have the > > complete list of devices which need the quirk applied when the patch > > first goes in? From my perspective, we definitely have one device > > which needs the quirk (and preferably, it'd be good to do it sooner > > than later so that we can get this bugfix out to our users) and an > > unknowable number of others. Would it be OK to introduce the quirk for > > just Pixelbook and to follow up to add others once we have that list? > > Totally-I've got no problem with this. oh-regarding Bill, yeah it might help a bit if you guys messaged them since I'm not in the vesa WG, I just have access to some specs from there > > > It may take a good amount of time for me to herd the cats inside > > Google, especially given there's a chance that there are affected > > laptops and that no one has noticed (e.g., I almost didn't notice with > > the Pixelbook). Given Lyude's analysis it seems like Chrome OS devices > > may be the largest affected group here, so I am incentivized to not > > drop the ball after fixing my immediate Pixelbook problem :) > > > > On Fri, Sep 25, 2020 at 10:53 AM Lyude Paul <lyude@xxxxxxxxxx> wrote: > > > On Thu, 2020-09-24 at 17:46 -0600, Kevin Chowski wrote: > > > > cc back a few others who were unintentionally dropped from the thread > > > > earlier. > > > > > > > > Someone (at Google) helped me dig into this a little more and they > > > > found a document titled "eDP Backlight Brightness bit alignment" sent > > > > out for review in January 2017. I registered for a new account (google > > > > is a member) and have access to the document; here is the URL for > > > > those who also have access: > > > > https://groups.vesa.org/wg/AllMem/document/7786. For what it's worth, > > > > it seems like Lyude's contact Bill Lempesis uploaded this > > > > change-request document, so I think we can reach out to him if we have > > > > further questions. It's actually unclear to me what the status of this > > > > change request is, and whether it's been officially accepted. But I > > > > think it can be seen as some official advice on how we can move > > > > forward here. > > > > > > > > Basically, this is a change request to the spec which acknowledges > > > > that, despite the original spec implying that the > > > > most-significant-bits were relevant here, many implementations used > > > > the least-significant-bits. In defense of most-significant it laid out > > > > some similar arguments to what Ville was saying. But it ends up > > > > saying: > > > > > > > > > Unfortunately, the most common interpretation that we have > > > > > encountered is case 1 in the example above. TCON vendors > > > > > tend to align the valid bits to the LSBs, not the MSBs. > > > > > > > > Instead of changing the default defined functionality (as some earlier > > > > version of this doc apparently suggested), this doc prefers to > > > > allocate two extra bits in EDP_GENERAL_CAPABILITY_2 so that future > > > > backlight devices can specify to the Source how to program them: > > > > > > > > 00: the current functionality, i,e. no defined interpretation > > > > 01: aligned to most-significant bits > > > > 10: aligned to least-significant bits > > > > 11: reserved > > > > > > > > It also says "[Sources] should only need panel-specific workarounds > > > > for the currently available panels." > > > > > > > > So I believe this document is an acknowledgement of many > > > > implementations having their alignment to the least-significant bits, > > > > and (to my eyes) clearly validates that the spec "should" be the > > > > opposite. If we believe the doc's claim that "the most common > > > > interpretation" is least-significant, it seems to me that it would > > > > require more quirks if we made most-significant the default > > > > implementation. > > > > > > > > Ville mentioned at some point earlier that we should try to match the > > > > spec, whereas Lyude mentioned we should prefer to do what the majority > > > > of machines do. What do you both think of this new development? > > > > > > That's how displayport happens to be sometimes :). Definitely isn't the > > > first > > > time something in the spec like this got implemented incorrectly so many > > > times > > > by different vendors that they had to update the spec in response (same > > > thing > > > happened with MST and interleaved sideband messages as of DP 2.0), so I'm > > > really glad we went and actually investigated this. > > > > > > So yes - I think a quirk for this would definitely be a good idea, and IMO > > > we > > > should always lean on the side that more panels implement even if it's not > > > according to spec - so defaulting to the behavior we currently have in the > > > kernel, and adding quirks for panels that were smart enough not to fall > > > for > > > this would probably be the best way to go. That just leaves the challenge > > > of > > > "how do we figure out which panels actually need this and which ones > > > don't?" > > > > > > This might end up being a bit of a challenge, but I've got some ideas on > > > how > > > we might be able to tackle it to the best of our ability based off my > > > discussions with laptop vendors. It seems like some of the homegrown > > > backlight > > > interfaces might help us out here. Note I'm mentioning other laptop > > > vendors > > > here because at least for nouveau, our plan for DPCD backlight support is > > > to > > > move a lot of the code for handling it that currently lives in i915 into > > > shared DRM helpers (which now we'll definitely need to do as a result of > > > these > > > quirks). > > > > > > So, on the x86 front, there's already a few different interfaces in use > > > for > > > laptop panels: > > > * AMD usually uses their own backlight interface, so for AMD-only laptops > > > we > > > can probably safely ignore this > > > * Intel uses their own DPCD backlight interface on most of the _non- > > > ChromeOS_ > > > machines on the market right now afaik based off my discussion with > > > some > > > laptop vendors. For panels that only come up in Intel-only machines, > > > that > > > means we only really need to care about the ChromeOS case here. So-if > > > Google's able to actually survey the devices they're shipping with > > > ChromeOS > > > right now to figure out which ones are using DPCD backlight controls, > > > and > > > which ones need to be MSB aligned - then I'd think we could probably > > > build > > > an accurate quirk list of those panels easily. > > > * This just leaves the nvidia case. Nvidia seems to be one of the only > > > GPU > > > vendors that didn't come up with their own backlight interface over > > > DPCD, > > > and they actually require that the panel support the VESA backlight > > > control > > > interface. Incidentally, a lot of the laptops that I've force-enabled > > > VESA > > > backlight controls on have nvidia GPUs in them, and so far every single > > > one > > > has worked with the code we currently use in the kernel. My hope with > > > this > > > would be that since nvidia's driver support is somewhat consistent, > > > they > > > either might have a list of problematic panels or can just verify with > > > us > > > that all of the panels that their driver interacts with follow the LSB > > > preference. > > > > > > For the ChromeOS guys in the thread, does this sound like it could be > > > workable? For the time being, I'll also send my nvidia contacts a poke to > > > see > > > what info they can give us. As well, we should probably poke Bill just in > > > case > > > he might know of some resource that documents some of the problematic > > > panels > > > out there (probably not, but it's at least worth a shot). I'll try to get > > > around this today, but we might have to poke him once or twice since there > > > originally was a problem with any of the emails from Red Hat getting > > > through > > > to him… > > > > > > > I will also look into whether my specific device supports this > > > > extension, and in that case I'll volunteer to implement this new > > > > functionality in the driver. > > > > > > > > Thanks for your time, > > > > Kevin > > > > > > > > On Tue, Sep 22, 2020 at 3:30 PM Lyude Paul <lyude@xxxxxxxxxx> wrote: > > > > > Hi! Since I got dropped from the thread, many responses inline > > > > > > > > > > On Tue, 2020-09-22 at 12:58 -0700, Puthikorn Voravootivat wrote: > > > > > > +Lyude > > > > > > I notice that Lyude email was somehow dropped from the thread. > > > > > > Lyude was the person who submitted the patch for Thinkpad and should > > > > > > know the OUI of the panel. > > > > > > > > > > no need - currently because of some confusion that got caused by the > > > > > Intel > > > > > HDR > > > > > backlight interface being the only backlight interface that works > > > > > properly > > > > > on > > > > > a lot of panels (many panels will advertise both interfaces, but might > > > > > only > > > > > work with the Intel one), we actually rely on a small allowlist of > > > > > "approved" > > > > > panels for enabling DPCD backlight control. > > > > > > > > > > …however, many of these panels are annoying and don't actually provide > > > > > a > > > > > reliable enough OUID to use for quirk detection, which is why we had > > > > > to > > > > > add > > > > > EDID quirk detection as a temporary workaround for this. The current > > > > > list > > > > > of > > > > > panels lives in drm_dp_helper.c: > > > > > > > > > > /* > > > > > * Some devices have unreliable OUIDs where they don't set the device > > > > > ID > > > > > * correctly, and as a result we need to use the EDID for finding > > > > > additional > > > > > * DP quirks in such cases. > > > > > */ > > > > > static const struct edid_quirk edid_quirk_list[] = { > > > > > /* Optional 4K AMOLED panel in the ThinkPad X1 Extreme 2nd > > > > > Generation > > > > > * only supports DPCD backlight controls > > > > > */ > > > > > { MFG(0x4c, 0x83), PROD_ID(0x41, 0x41), > > > > > BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) }, > > > > > /* > > > > > * Some Dell CML 2020 systems have panels support both AUX and > > > > > PWM > > > > > * backlight control, and some only support AUX backlight > > > > > control. > > > > > All > > > > > * said panels start up in AUX mode by default, and we don't > > > > > have > > > > > any > > > > > * support for disabling HDR mode on these panels which would > > > > > be > > > > > * required to switch to PWM backlight control mode (plus, I'm > > > > > not > > > > > * even sure we want PWM backlight controls over DPCD > > > > > backlight > > > > > * controls anyway...). Until we have a better way of > > > > > detecting > > > > > these, > > > > > * force DPCD backlight mode on all of them. > > > > > */ > > > > > { MFG(0x06, 0xaf), PROD_ID(0x9b, 0x32), > > > > > BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) }, > > > > > { MFG(0x06, 0xaf), PROD_ID(0xeb, 0x41), > > > > > BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) }, > > > > > { MFG(0x4d, 0x10), PROD_ID(0xc7, 0x14), > > > > > BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) }, > > > > > { MFG(0x4d, 0x10), PROD_ID(0xe6, 0x14), > > > > > BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) }, > > > > > { MFG(0x4c, 0x83), PROD_ID(0x47, 0x41), > > > > > BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) }, > > > > > }; > > > > > > > > > > Also note that I think just about every panel on that list supports > > > > > the > > > > > Intel > > > > > HDR backlight interface, so it's -possible- that the VESA interface > > > > > could > > > > > be > > > > > broken on these panels. But, that would be a lot of different panels > > > > > from > > > > > different vendors to all be broken in the same way. > > > > > > > > > > > On Tue, Sep 22, 2020 at 11:47 AM Kevin Chowski <chowski@xxxxxxxxxxxx > > > > > > > > > > > > > wrote: > > > > > > > Alrighty, I'll take everyone else's silence as tacit approval of > > > > > > > Ville's opinions. (I didn't receive any email bounces this time, > > > > > > > so > > > > > > > I > > > > > > > think my issue was transient.) I will start on inverting the quirk > > > > > > > and > > > > > > > making the most-significant-alignment matter for these registers > > > > > > > by > > > > > > > default. > > > > > > > > > > > > > > Who can help me gather a list of OUIs that we need to add to the > > > > > > > quirk? I can follow up with Puthikorn about the relevant > > > > > > > Chromebooks, > > > > > > > but I don't know what other types of laptops are using this > > > > > > > driver. > > > > > > > > > > > > > > Thanks for your time, > > > > > > > Kevin Chowski > > > > > > > > > > > > > > > > > > > > > On Fri, Sep 18, 2020 at 12:16 PM Puthikorn Voravootivat > > > > > > > <puthik@xxxxxxxxxxxx> wrote: > > > > > > > > I'll defer to Ville & Lyude. > > > > > > > > > > > > > > > > I dug up more on the bug report and found that both Thinkpad and > > > > > > > > Galaxy Chromebook use the same Samsung OLED. > > > > > > > > So my 2 vs 1 argument is actually not valid. > > > > > > > > > > > > > > > > On Fri, Sep 18, 2020 at 10:59 AM Kevin Chowski < > > > > > > > > chowski@xxxxxxxxxxxx > > > > > > > > wrote: > > > > > > > > > Apologies once again, some of my emails were bouncing for some > > > > > > > > > addresses yesterday. Hopefully it was a temporary condition; > > > > > > > > > I'll > > > > > > > > > continue trying to dig into it on my end if it happens again > > > > > > > > > for > > > > > > > > > this > > > > > > > > > email. > > > > > > > > > > > > > > > > > > Since there's evidence that some models want lsb and some > > > > > > > > > (well, > > > > > > > > > at > > > > > > > > > least one) want msb, my understanding is that we'll need a > > > > > > > > > quirk > > > > > > > > > one > > > > > > > > > way or the other (please correct if I'm mistaken). I > > > > > > > > > unfortunately > > > > > > > > > don't have the ability to test anything other than the > > > > > > > > > Pixelbook, > > > > > > > > > so > > > > > > > > > if we decide the msb is the "right" way, then I will have to > > > > > > > > > rely > > > > > > > > > on > > > > > > > > > others to test (and find the OUI of) other models which > > > > > > > > > require > > > > > > > > > lsb. > > > > > > > > > > > > > > > > > > I am happy to make any changes requested, but I do not at all > > > > > > > > > have > > > > > > > > > enough background here to make the decision on whether the msb > > > > > > > > > functionality deserves the quirk or if the lsb one does. How > > > > > > > > > can > > > > > > > > > I > > > > > > > > > help you all come to an agreement here? > > > > > > > > > > > > > > > > > > * It seems like Ville feels strongly about the msb being the > > > > > > > > > correct > > > > > > > > > interpretation of the spec. > > > > > > > > > * It's unclear to me on which side of the fence Lyude falls, I > > > > > > > > > couldn't pick up a strong opinion in her clarifying question. > > > > > > > > > * Puthikorn seems to be on the side of lsb being correct, but > > > > > > > > > maybe > > > > > > > > > was swayed by Ville's argument. > > > > > > > > > > Honestly I'm not hard to convince :P, if it looks like we got the bit > > > > > shift > > > > > wrong for the majority of devices and everyone else agrees then I'm > > > > > fine > > > > > with > > > > > assuming that's the case. I'm just quite surprised, seeing as we've > > > > > tested > > > > > many different panels from a few vendors and haven't run into any > > > > > issues > > > > > with > > > > > this before. > > > > > > > > > > Honestly - if there's this much uncertainty about it, maybe we should > > > > > just > > > > > ask > > > > > VESA directly what the correct interpretation of this is? Note I'm not > > > > > on > > > > > the > > > > > VESA board (I get access to DP/eDP specs through X.org) so unless the > > > > > contacts > > > > > I've got from VESA would work (Bill Lempesis bill at vesa dot org) for > > > > > that it > > > > > might be a better idea for someone from Google or Intel to ask. > > > > > > > > > > > > > > If no one feels that Ville's argument is not strong in some > > > > > > > > > way, > > > > > > > > > and > > > > > > > > > we go with that, I will get to work on the requested changes. > > > > > > > > > I > > > > > > > > > am > > > > > > > > > concerned, though, about changing the default functionality > > > > > > > > > without > > > > > > > > > testing it widely to find the set of laptops which require the > > > > > > > > > lsb > > > > > > > > > quirk. I'd appreciate any advice people might have about > > > > > > > > > making > > > > > > > > > this > > > > > > > > > change safely. > > > > > > > > > > Usually, I just try to stick with what the majority of machines need > > > > > to > > > > > do. I > > > > > still think it'd be a good idea for us to verify this with VESA if > > > > > there's > > > > > that much confusion though > > > > > > > > > > > > > > Thank you for your time, > > > > > > > > > Kevin > > > > > > > > > > > > > > > > > > On Thu, Sep 17, 2020 at 2:11 PM Ville Syrjälä > > > > > > > > > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > > On Thu, Sep 17, 2020 at 09:25:35PM +0300, Ville Syrjälä > > > > > > > > > > wrote: > > > > > > > > > > > On Thu, Sep 17, 2020 at 11:14:43AM -0700, Puthikorn > > > > > > > > > > > Voravootivat > > > > > > > > > > > wrote: > > > > > > > > > > > > The Lyude fde7266fb2f6 change is actually based on > > > > > > > > > > > > Chromium > > > > > > > > > > > > change > > > > > > > > > > > > (https://crrev.com/c/1650325) that fixes the brightness > > > > > > > > > > > > for > > > > > > > > > > > > Samsung > > > > > > > > > > > > Galaxy Chromebook. So currently we have 2 examples that > > > > > > > > > > > > use > > > > > > > > > > > > LSB > > > > > > > > > > > > interpretation and 1 that use MSB. > > > > > > > > > > > > > > > > > > > > > > "If field 4:0 of the EDP_PWMGEN_BIT_COUNT register > > > > > > > > > > > represents > > > > > > > > > > > a > > > > > > > > > > > value > > > > > > > > > > > of greater than 8 and the BACKLIGHT_BRIGHTNESS_BYTE_COUNT > > > > > > > > > > > bit > > > > > > > > > > > is cleared to 0, only the 8 MSB of the brightness control > > > > > > > > > > > value > > > > > > > > > > > can be > > > > > > > > > > > controlled. > > > > > > > > > > > (See Note below.) > > > > > > > > > > > Assigned bits are allocated to the MSB of the enabled > > > > > > > > > > > register > > > > > > > > > > > combination." > > > > > > > > > > > > > > > > > > > > > > I think that's pretty clear the assigned bits are supposed > > > > > > > > > > > to > > > > > > > > > > > be > > > > > > > > > > > msb aligned. > > > > > > > > > > > > > > > > > > > > I guess there's some email issues happening, but just to > > > > > > > > > > clarify: > > > > > > > > > > > > > > > > > > > > When the spec says MSB in caps here it clearly means > > > > > > > > > > "most significant-bit(s)" since otherwise "8 MSB" would not > > > > > > > > > > make > > > > > > > > > > any sense in the context of a 2 byte value. > > > > > > > > > > > > > > > > > > > > Granted the spec is crap here since "Table 1-1: Acronyms and > > > > > > > > > > Initialism" does claim "MSB" should be byte(s) and "msb" > > > > > > > > > > bit(s). > > > > > > > > > > > > > > > > > > > > Also I can't imagine anyone would allocate the bits starting > > > > > > > > > > from the lsb when the whole thing is clearly supposed to be > > > > > > > > > > a > > > > > > > > > > 16bit big endian integer. So with >8 assigned bits you'd end > > > > > > > > > > up with crazy stuff like this: > > > > > > > > > > > > > > > > > > > > [ 7 ... 0 ][7 ... 0] > > > > > > > > > > [ 8 MSB ][XXXX][N LSB] > > > > > > > > > > > > > > > > > > > > so you couldn't even treat the value as a regular big endian > > > > > > > > > > thing. Instead, if you squint a bit, it now looks like a > > > > > > > > > > funky > > > > > > > > > > little endian value. So we're deep into some mixed endian > > > > > > > > > > land > > > > > > > > > > where nothing makes sense anymore. > > > > > > > > > > > > > > > > > > > > Anyways I think the code should simply do this to match the > > > > > > > > > > spec: > > > > > > > > > > u16 value = brightness << (16 - num_assigned_bits); > > > > > > > > > > val[0] = value >> 8; > > > > > > > > > > val[1] = value & 0xff; > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Sep 17, 2020 at 10:55 AM Kevin Chowski < > > > > > > > > > > > > chowski@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > > Apologies for being too vague. To be as precise I can > > > > > > > > > > > > > be, > > > > > > > > > > > > > here > > > > > > > > > > > > > is the > > > > > > > > > > > > > specific code delta I tested: > > > > > > > > > > > > > https://crrev.com/c/2406616 > > > > > > > > > > > > > . To > > > > > > > > > > > > > answer > > > > > > > > > > > > > your other question, the code I tested against is > > > > > > > > > > > > > indeed > > > > > > > > > > > > > including the > > > > > > > > > > > > > fde7266fb2f6 (despite ostensibly being called 5.4 in > > > > > > > > > > > > > my > > > > > > > > > > > > > commit > > > > > > > > > > > > > message): our current top-of-tree for our 5.4 branch > > > > > > > > > > > > > includes > > > > > > > > > > > > > the > > > > > > > > > > > > > intel_dp_aux_calc_max_backlight logic. Further, I'll > > > > > > > > > > > > > note > > > > > > > > > > > > > that > > > > > > > > > > > > > change > > > > > > > > > > > > > is exactly the change which breaks my Pixelbook model: > > > > > > > > > > > > > prior > > > > > > > > > > > > > to the > > > > > > > > > > > > > change, the max_brightness was hard-coded to 0xFFFF > > > > > > > > > > > > > and > > > > > > > > > > > > > the > > > > > > > > > > > > > math > > > > > > > > > > > > > worked out that it didn't matter that the hardware > > > > > > > > > > > > > cared > > > > > > > > > > > > > about > > > > > > > > > > > > > the MSB > > > > > > > > > > > > > despite the driver code caring about the LSB. > > > > > > > > > > > > > > > > > > > > > > > > > > To answer Ville's question: the fde7266fb2f6 change > > > > > > > > > > > > > which > > > > > > > > > > > > > fixes one > > > > > > > > > > > > > laptop (I believe Thinkpad X1 extreme Gen 2, from some > > > > > > > > > > > > > bug > > > > > > > > > > > > > reports I > > > > > > > > > > > > > dug up) and breaks another (Pixelbook); so > > > > > > > > > > > > > unfortunately > > > > > > > > > > > > > I > > > > > > > > > > > > > believe we > > > > > > > > > > > > > need a quirk at least for some laptop. Reading through > > > > > > > > > > > > > the > > > > > > > > > > > > > copy of the > > > > > > > > > > > > > datasheet I have, it wasn't clear to me which was the > > > > > > > > > > > > > correct > > > > > > > > > > > > > interpretation. I'm cc'ing puthik@, who was leaning > > > > > > > > > > > > > toward > > > > > > > > > > > > > the > > > > > > > > > > > > > current > > > > > > > > > > > > > kernel code (caring about LSB) being the correct > > > > > > > > > > > > > interpretation. I > > > > > > > > > > > > > believe we have other chromebooks which do rely on LSB > > > > > > > > > > > > > functionality, > > > > > > > > > > > > > so unless we can find more examples of laptops wanting > > > > > > > > > > > > > MSB > > > > > > > > > > > > > it > > > > > > > > > > > > > currently looks like Pixelbook is the outlier. > > > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Sep 17, 2020 at 11:28 AM Jani Nikula > > > > > > > > > > > > > <jani.nikula@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > On Thu, 17 Sep 2020, Kevin Chowski < > > > > > > > > > > > > > > chowski@xxxxxxxxxxxx > > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > We have observed that Google Pixelbook's backlight > > > > > > > > > > > > > > > hardware is > > > > > > > > > > > > > > > interpretting these backlight bits from the most- > > > > > > > > > > > > > > > significant side of the > > > > > > > > > > > > > > > 16 bit word (if DP_EDP_PWMGEN_BIT_COUNT < 16), > > > > > > > > > > > > > > > whereas > > > > > > > > > > > > > > > the > > > > > > > > > > > > > > > driver code > > > > > > > > > > > > > > > assumes the peripheral cares about the least- > > > > > > > > > > > > > > > significant > > > > > > > > > > > > > > > bits. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Testing was done from within Chrome OS's build > > > > > > > > > > > > > > > environment > > > > > > > > > > > > > > > when the > > > > > > > > > > > > > > > patch is backported to 5.4 (the version we are > > > > > > > > > > > > > > > newly > > > > > > > > > > > > > > > targeting for the > > > > > > > > > > > > > > > Pixelbook); for the record: > > > > > > > > > > > > > > > $ emerge-eve-kernelnext sys-kernel/chromeos- > > > > > > > > > > > > > > > kernel- > > > > > > > > > > > > > > > 5_4 > > > > > > > > > > > > > > > && \ > > > > > > > > > > > > > > > ./update_kernel.sh --remote=$IP > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I used `/sys/kernel/debug/dri/0/eDP-1/i915_dpcd` > > > > > > > > > > > > > > > on > > > > > > > > > > > > > > > my > > > > > > > > > > > > > > > laptop to verify > > > > > > > > > > > > > > > that the registers were being set according to > > > > > > > > > > > > > > > what > > > > > > > > > > > > > > > the > > > > > > > > > > > > > > > actual hardware > > > > > > > > > > > > > > > expects; I also observe that the backlight is > > > > > > > > > > > > > > > noticeably > > > > > > > > > > > > > > > brighter with > > > > > > > > > > > > > > > this patch. > > > > > > > > > > > > > > > > > > > > > > > > > > > > It's unclear to me what kernel version this is > > > > > > > > > > > > > > against, > > > > > > > > > > > > > > and > > > > > > > > > > > > > > what you've > > > > > > > > > > > > > > actually tested. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Have you tried v5.7 kernel with Lyude's fde7266fb2f6 > > > > > > > > > > > > > > ("drm/i915: Fix eDP > > > > > > > > > > > > > > DPCD aux max backlight calculations")? > > > > > > > > > > > > > > > > > > > > > > > > > > > > I just want to make sure you've tested with all the > > > > > > > > > > > > > > relevant > > > > > > > > > > > > > > fixes > > > > > > > > > > > > > > before adding quirks. > > > > > > > > > > > > > > > > > > > > > > > > > > > > BR, > > > > > > > > > > > > > > Jani. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Kevin Chowski <chowski@xxxxxxxxxxxx > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > .../drm/i915/display/intel_dp_aux_backlight.c | > > > > > > > > > > > > > > > 34 > > > > > > > > > > > > > > > +++++++++++++++++++ > > > > > > > > > > > > > > > drivers/gpu/drm/i915/display/intel_quirks.c | > > > > > > > > > > > > > > > 13 > > > > > > > > > > > > > > > +++++++ > > > > > > > > > > > > > > > drivers/gpu/drm/i915/i915_drv.h | > > > > > > > > > > > > > > > 1 > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > 3 files changed, 48 insertions(+) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > diff --git > > > > > > > > > > > > > > > a/drivers/gpu/drm/i915/display/intel_dp_aux_backli > > > > > > > > > > > > > > > gh > > > > > > > > > > > > > > > t. > > > > > > > > > > > > > > > c > > > > > > > > > > > > > > > b/drivers/gpu/drm/i915/display/intel_dp_aux_backli > > > > > > > > > > > > > > > gh > > > > > > > > > > > > > > > t. > > > > > > > > > > > > > > > c > > > > > > > > > > > > > > > index acbd7eb66cbe3..99c98f217356d 100644 > > > > > > > > > > > > > > > --- > > > > > > > > > > > > > > > a/drivers/gpu/drm/i915/display/intel_dp_aux_backli > > > > > > > > > > > > > > > gh > > > > > > > > > > > > > > > t. > > > > > > > > > > > > > > > c > > > > > > > > > > > > > > > +++ > > > > > > > > > > > > > > > b/drivers/gpu/drm/i915/display/intel_dp_aux_backli > > > > > > > > > > > > > > > gh > > > > > > > > > > > > > > > t. > > > > > > > > > > > > > > > c > > > > > > > > > > > > > > > @@ -91,6 +91,23 @@ static u32 > > > > > > > > > > > > > > > intel_dp_aux_get_backlight(struct intel_connector > > > > > > > > > > > > > > > *connector) > > > > > > > > > > > > > > > if (intel_dp->edp_dpcd[2] & > > > > > > > > > > > > > > > DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) > > > > > > > > > > > > > > > level = (read_val[0] << 8 | > > > > > > > > > > > > > > > read_val[1]); > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + if (i915->quirks & > > > > > > > > > > > > > > > QUIRK_SHIFT_EDP_BACKLIGHT_BRIGHTNESS) { > > > > > > > > > > > > > > > + if (!drm_dp_dpcd_readb(&intel_dp- > > > > > > > > > > > > > > > >aux, > > > > > > > > > > > > > > > DP_EDP_PWMGEN_BIT_COUNT, > > > > > > > > > > > > > > > + &rea > > > > > > > > > > > > > > > d_ > > > > > > > > > > > > > > > va > > > > > > > > > > > > > > > l[0] > > > > > > > > > > > > > > > )) { > > > > > > > > > > > > > > > + DRM_DEBUG_KMS("Failed to > > > > > > > > > > > > > > > read > > > > > > > > > > > > > > > DPCD > > > > > > > > > > > > > > > register 0x%x\n", > > > > > > > > > > > > > > > + DP_EDP_PWMGE > > > > > > > > > > > > > > > N_ > > > > > > > > > > > > > > > BI > > > > > > > > > > > > > > > T_CO > > > > > > > > > > > > > > > UNT); > > > > > > > > > > > > > > > + return 0; > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > + // Only bits 4:0 are used, 7:5 are > > > > > > > > > > > > > > > reserved. > > > > > > > > > > > > > > > + read_val[0] = read_val[0] & 0x1F; > > > > > > > > > > > > > > > + if (read_val[0] > 16) { > > > > > > > > > > > > > > > + DRM_DEBUG_KMS("Invalid > > > > > > > > > > > > > > > DP_EDP_PWNGEN_BIT_COUNT 0x%X, expected at most > > > > > > > > > > > > > > > 16\n", > > > > > > > > > > > > > > > + read > > > > > > > > > > > > > > > _v > > > > > > > > > > > > > > > al > > > > > > > > > > > > > > > [0]) > > > > > > > > > > > > > > > ; > > > > > > > > > > > > > > > + return 0; > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > + level >>= 16 - read_val[0]; > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > return level; > > > > > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > @@ -106,6 +123,23 @@ > > > > > > > > > > > > > > > intel_dp_aux_set_backlight(const > > > > > > > > > > > > > > > struct drm_connector_state *conn_state, u32 lev > > > > > > > > > > > > > > > struct drm_i915_private *i915 = > > > > > > > > > > > > > > > dp_to_i915(intel_dp); > > > > > > > > > > > > > > > u8 vals[2] = { 0x0 }; > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > + if (i915->quirks & > > > > > > > > > > > > > > > QUIRK_SHIFT_EDP_BACKLIGHT_BRIGHTNESS) { > > > > > > > > > > > > > > > + if (!drm_dp_dpcd_readb(&intel_dp- > > > > > > > > > > > > > > > >aux, > > > > > > > > > > > > > > > DP_EDP_PWMGEN_BIT_COUNT, > > > > > > > > > > > > > > > + &val > > > > > > > > > > > > > > > s[ > > > > > > > > > > > > > > > 0] > > > > > > > > > > > > > > > )) { > > > > > > > > > > > > > > > + DRM_DEBUG_KMS("Failed to > > > > > > > > > > > > > > > write > > > > > > > > > > > > > > > aux > > > > > > > > > > > > > > > backlight level: Failed to read DPCD register > > > > > > > > > > > > > > > 0x%x\n", > > > > > > > > > > > > > > > + DP_EDP_PWM > > > > > > > > > > > > > > > GE > > > > > > > > > > > > > > > N_ > > > > > > > > > > > > > > > BIT_ > > > > > > > > > > > > > > > COUNT); > > > > > > > > > > > > > > > + return; > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > + // Only bits 4:0 are used, 7:5 are > > > > > > > > > > > > > > > reserved. > > > > > > > > > > > > > > > + vals[0] = vals[0] & 0x1F; > > > > > > > > > > > > > > > + if (vals[0] > 16) { > > > > > > > > > > > > > > > + DRM_DEBUG_KMS("Failed to > > > > > > > > > > > > > > > write > > > > > > > > > > > > > > > aux > > > > > > > > > > > > > > > backlight level: Invalid DP_EDP_PWNGEN_BIT_COUNT > > > > > > > > > > > > > > > 0x%X, > > > > > > > > > > > > > > > expected at most 16\n", > > > > > > > > > > > > > > > + vals > > > > > > > > > > > > > > > [0 > > > > > > > > > > > > > > > ]) > > > > > > > > > > > > > > > ; > > > > > > > > > > > > > > > + return; > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > + level <<= (16 - vals[0]) & 0xFFFF; > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > vals[0] = level; > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > /* Write the MSB and/or LSB */ > > > > > > > > > > > > > > > diff --git > > > > > > > > > > > > > > > a/drivers/gpu/drm/i915/display/intel_quirks.c > > > > > > > > > > > > > > > b/drivers/gpu/drm/i915/display/intel_quirks.c > > > > > > > > > > > > > > > index 46beb155d835f..63b27d49b2864 100644 > > > > > > > > > > > > > > > --- a/drivers/gpu/drm/i915/display/intel_quirks.c > > > > > > > > > > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_quirks.c > > > > > > > > > > > > > > > @@ -53,6 +53,16 @@ static void > > > > > > > > > > > > > > > quirk_increase_ddi_disabled_time(struct > > > > > > > > > > > > > > > drm_i915_private > > > > > > > > > > > > > > > *i915) > > > > > > > > > > > > > > > drm_info(&i915->drm, "Applying Increase DDI > > > > > > > > > > > > > > > Disabled > > > > > > > > > > > > > > > quirk\n"); > > > > > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > +/* > > > > > > > > > > > > > > > + * Some eDP backlight hardware uses the most- > > > > > > > > > > > > > > > significant > > > > > > > > > > > > > > > bits of the brightness > > > > > > > > > > > > > > > + * register, so brightness values must be shifted > > > > > > > > > > > > > > > first. > > > > > > > > > > > > > > > + */ > > > > > > > > > > > > > > > +static void > > > > > > > > > > > > > > > quirk_shift_edp_backlight_brightness(struct > > > > > > > > > > > > > > > drm_i915_private *i915) > > > > > > > > > > > > > > > +{ > > > > > > > > > > > > > > > + i915->quirks |= > > > > > > > > > > > > > > > QUIRK_SHIFT_EDP_BACKLIGHT_BRIGHTNESS; > > > > > > > > > > > > > > > + DRM_INFO("Applying shift eDP backlight > > > > > > > > > > > > > > > brightness > > > > > > > > > > > > > > > quirk\n"); > > > > > > > > > > > > > > > +} > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > struct intel_quirk { > > > > > > > > > > > > > > > int device; > > > > > > > > > > > > > > > int subsystem_vendor; > > > > > > > > > > > > > > > @@ -156,6 +166,9 @@ static struct intel_quirk > > > > > > > > > > > > > > > intel_quirks[] = { > > > > > > > > > > > > > > > /* ASRock ITX*/ > > > > > > > > > > > > > > > { 0x3185, 0x1849, 0x2212, > > > > > > > > > > > > > > > quirk_increase_ddi_disabled_time }, > > > > > > > > > > > > > > > { 0x3184, 0x1849, 0x2212, > > > > > > > > > > > > > > > quirk_increase_ddi_disabled_time }, > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > + /* Google Pixelbook */ > > > > > > > > > > > > > > > + { 0x591E, 0x8086, 0x2212, > > > > > > > > > > > > > > > quirk_shift_edp_backlight_brightness }, > > > > > > > > > > > > > > > }; > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > void intel_init_quirks(struct drm_i915_private > > > > > > > > > > > > > > > *i915) > > > > > > > > > > > > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h > > > > > > > > > > > > > > > b/drivers/gpu/drm/i915/i915_drv.h > > > > > > > > > > > > > > > index e4f7f6518945b..cc93bede4fab8 100644 > > > > > > > > > > > > > > > --- a/drivers/gpu/drm/i915/i915_drv.h > > > > > > > > > > > > > > > +++ b/drivers/gpu/drm/i915/i915_drv.h > > > > > > > > > > > > > > > @@ -525,6 +525,7 @@ struct i915_psr { > > > > > > > > > > > > > > > #define QUIRK_PIN_SWIZZLED_PAGES (1<<5) > > > > > > > > > > > > > > > #define QUIRK_INCREASE_T12_DELAY (1<<6) > > > > > > > > > > > > > > > #define QUIRK_INCREASE_DDI_DISABLED_TIME (1<<7) > > > > > > > > > > > > > > > +#define QUIRK_SHIFT_EDP_BACKLIGHT_BRIGHTNESS > > > > > > > > > > > > > > > (1<<8) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > struct intel_fbdev; > > > > > > > > > > > > > > > struct intel_fbc_work; > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > Jani Nikula, Intel Open Source Graphics Center > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > Ville Syrjälä > > > > > > > > > > > Intel > > > > > > > > > > > _______________________________________________ > > > > > > > > > > > Intel-gfx mailing list > > > > > > > > > > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > > > > > > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > Ville Syrjälä > > > > > > > > > > Intel > > > > > -- > > > > > Cheers, > > > > > Lyude Paul (she/her) > > > > > Software Engineer at Red Hat > > > > > > > > -- > > > Cheers, > > > Lyude Paul (she/her) > > > Software Engineer at Red Hat > > > -- Sincerely, Lyude Paul (she/her) Software Engineer at Red Hat _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
