On Thu, Mar 01, 2012 at 10:19:58AM +0100, Corentin Chary wrote: > On Wed, Feb 29, 2012 at 11:56 PM, Seth Forshee > <seth.forshee@xxxxxxxxxxxxx> wrote: > > On Wed, Feb 29, 2012 at 04:32:28PM -0600, Grant Likely wrote: > >> On Wed, Feb 29, 2012 at 4:08 PM, Seth Forshee > >> <seth.forshee@xxxxxxxxxxxxx> wrote: > >> > On Wed, Feb 29, 2012 at 03:23:20PM -0600, Grant Likely wrote: > >> >> On Wed, Feb 29, 2012 at 1:50 PM, Seth Forshee > >> >> <seth.forshee@xxxxxxxxxxxxx> wrote: > >> >> > On Wed, Feb 29, 2012 at 12:43:23PM -0600, Grant Likely wrote: > >> >> >> On Wed, Feb 29, 2012 at 11:53 AM, Seth Forshee > >> >> >> <seth.forshee@xxxxxxxxxxxxx> wrote: > >> >> >> > On Wed, Feb 29, 2012 at 11:46:39AM -0600, Grant Likely wrote: > >> >> >> >> On Wed, Feb 22, 2012 at 8:37 AM, Seth Forshee > >> >> >> >> <seth.forshee@xxxxxxxxxxxxx> wrote: > >> >> >> >> > Apple laptops with hybrid graphics have a device named gmux that > >> >> >> >> > controls the muxing of the LVDS panel between the GPUs as well as screen > >> >> >> >> > brightness. This driver adds support for the gmux device. Only backlight > >> >> >> >> > control is supported initially. > >> >> >> >> > > >> >> >> >> > Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > >> >> >> >> > >> >> >> >> Works for me. > >> >> >> >> > >> >> >> >> Tested-by: Grant Likely <grant.likely@xxxxxxxxxxxx> > >> >> >> >> > >> >> >> >> Now I just need to figure out how to get the desktop backlight widget > >> >> >> >> to use gmux_backlight instead of acpi_video0... > >> >> >> > > >> >> >> > The easy way is to pass acpi_backlight=vendor to the kernel, then you > >> >> >> > won't have acpi_vidoe0. > >> >> >> > >> >> >> That did it, thanks. I'm assume something is in the works to set it > >> >> >> up automatically? > >> >> > > >> >> > Not that I'm aware of. A number machines have this problem, that the > >> >> > standard ACPI backlight interfaces are implemented but don't work. This > >> >> > generally isn't detectable in software; with the Apples at least > >> >> > everything looks like it's working except that the brightness doesn't > >> >> > change (but not all Apple laptops are affected, so qurking based on > >> >> > manufacturer wouldn't work). All we're left with is DMI quirking, which > >> >> > isn't practical. Maybe we could add something so a platform driver can > >> >> > tell acpi_video that it knows the ACPI backlight doesn't work, but I > >> >> > think on some platforms that still is going to be based off of DMI > >> >> > information. > >> >> > >> >> blacklisting based on specific product name (ie. MacBookPro8,*) or > >> >> machine model is probably the best. It wouldn't be the first > >> >> blacklist in the linux kernel. > >> > > >> > I think the blacklist would have to be against specific product names. > >> > For example, the MacBook Pro 8,1 has a working acpi_video backlight and > >> > no gmux_backlight, the 8,2 has both but only gmux_backlight works, and I > >> > suspect the 8,3 is the same as the 8,2. > >> > >> I have the 8,3, and my testing confirms that. > >> > >> > We'd probably end up with an > >> > entry in the blacklist for every single model whose acpi_video backlight > >> > doesn't work, adding entries for each new generation of MacBooks. > >> > > >> > And if we start blacklisting Macs we'd have start doing it for other > >> > machines too, I guess. From what I've seen, open-ended blacklists like > >> > this get nacked pretty consistently nowadays. > >> > >> An alternative would be to blacklist or disable acpi0_backlight when > >> the apple-gmux driver loads. I don't know how acceptable that is, but > >> I also don't have much sympathy for nacking blacklists if there isn't > >> a viable alternative. > > > > Yes, that's one idea I was thinking about. For all the machines I've > > been able to get tested, if the gmux is present then it can control the > > backlight and acpi_video cannot, so that approach is reasonable for > > Macs. > > > > There are quite a few machines in this situation though, and whatever > > solution is arrived at should be flexible enough to work beyond just > > Macs. I'll try to find some time soon to explore this further and see if > > I can come up with something. > > Old Samsung laptops have the same issue, and I ended up patching > drivers/acpi/video_detect.c (check "[PATCH] ACPI / Video: blacklist > some samsung laptops"). > Doing it in the vendor module is complicated, since, it will be loaded > after the acpi video module most of the time, and that means addding > acpi_backlight, then removing it, which will probably confuse > usespace. > Patching drivers/acpi/video_detect.c seems safer. I certainly agree that it's the easiest solution, so maybe it is worth trying first and seeing what the response is. But last I saw the patch you're referring to hadn't been merged or even commented on yet. And I can't help but note that you included as justification for the patch that the acpi_video backlight works on newer Samsungs so the list wouldn't grow ;) Beyond Samsung and Apple I know that there are also Toshibas that suffer from this, and judging by the list from older versions of g-s-d [1] I'd say there may well be others. Seth [1] http://git.gnome.org/browse/gnome-settings-daemon/tree/plugins/power/gsd-backlight-helper.c?id=GNOME_SETTINGS_DAEMON_3_2_2#n50 -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
