On Wed, Aug 26, 2020 at 12:40:15PM +0800, Kai-Heng Feng wrote: > Hi, > > > On Aug 25, 2020, at 02:46, Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx> wrote: > > > > I remember some strangeness about the blnclegdisbl. I'll see if I can dig up some more. > > > The register read can be found at [1] and [2]. > > [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comments/119 > [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comments/120 Looks like it's using the 400mV/0dB setting. Can we get the same dumps with the driver loaded just to confirm whether we're using different settings? Also a dump of /sys/kernel/debug/dri/0/i915_vbt would be good to have. > > Kai-Heng > > > > > -----Original Message----- > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > Sent: Monday, August 24, 2020 11:05 AM > > To: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> > > Cc: Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx>; Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>; intel-gfx <intel-gfx@xxxxxxxxxxxxxxxxxxxxx> > > Subject: Re: [Regression] "drm/i915: Implement display w/a #1143" breaks HDMI on ASUS GL552VW > > > > On Mon, Aug 17, 2020 at 02:17:49PM +0800, Kai-Heng Feng wrote: > >> > >> > >>> On Aug 17, 2020, at 00:22, Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx> wrote: > >>> > >>> You'll need to read out the DDI_BUF_TRANS_* and DISPIO_CR_TX_BMU_CR0 registers at boot before i915 programs them and compare with what driver programs. > >>> Rodrigo can probably show you how. > >> > >> Right, I'll wait for a patch then :) > > > > To grab the BIOS reg values we just have to make sure the driver doesn't load. Eg. pass something like "modprobe.blacklist=i915,snd_hda_intel 3" to the kernel cmdline (+ whatever other magic ubuntu might require). Confirm with something like "lsmod | grep i915" to make sure the driver didn't sneak in despite our best efforts. > > > > Then we can dump the registers with intel_reg from igt-gpu-tools: > > intel_reg read --count 20 0x64E00 0x64E60 0x64EC0 0x64F20 0x64F80 intel_reg read 0x64000 0x64100 0x64200 0x64300 0x64400 0x6C00C > > > > The only somewhat suspicious thing I noticed is that we treat DISPIO_CR_TX_BMU_CR0:tx_blnclegdisbl as a bitmask (bit 23 -> DDI A, bit 24 -> DDI B, etc.) whereas the spec seems to be saying that we should just zero out all the bits of tx_blnclegdisbl when any DDI needs iboost. Art, is our interpretation of the bits correct or just a fairy tale? > > > >> > >> Kai-Heng > >> > >>> > >>> -----Original Message----- > >>> From: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> > >>> Sent: Thursday, August 13, 2020 10:14 PM > >>> To: Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx> > >>> Cc: Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>; Ville Syrjälä > >>> <ville.syrjala@xxxxxxxxxxxxxxx>; intel-gfx > >>> <intel-gfx@xxxxxxxxxxxxxxxxxxxxx> > >>> Subject: Re: [Regression] "drm/i915: Implement display w/a #1143" > >>> breaks HDMI on ASUS GL552VW > >>> > >>> Hi, > >>> > >>>> On Aug 14, 2020, at 01:56, Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx> wrote: > >>>> > >>>> The workaround is freeing up stuck vswing values to let new vswing programming kick in. Maybe the new vswing values are wrong. > >>>> Try checking the vswing that driver programs against what BIOS/GOP programs. > >>> > >>> Do you mean to print out value of I915_READ()? > >>> val = I915_READ(CHICKEN_TRANS(transcoder)); > >>> > >>> Kai-Heng > >>> > >>>> > >>>> -----Original Message----- > >>>> From: Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx> > >>>> Sent: Thursday, August 13, 2020 9:50 AM > >>>> To: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>; Runyan, Arthur J > >>>> <arthur.j.runyan@xxxxxxxxx> > >>>> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>; intel-gfx > >>>> <intel-gfx@xxxxxxxxxxxxxxxxxxxxx> > >>>> Subject: Re: [Regression] "drm/i915: Implement display w/a #1143" > >>>> breaks HDMI on ASUS GL552VW > >>>> > >>>> Art, any comment here? > >>>> > >>>> I just checked and the W/a 1143 is implemented as described, but it is failing HDMI on this hybrid system. > >>>> > >>>>> On Aug 12, 2020, at 9:07 PM, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: > >>>>> > >>>>> Hi, > >>>>> > >>>>> There's a regression reported that HDMI output stops working after os upgrade: > >>>>> https://bugs.launchpad.net/bugs/1871721 > >>>>> > >>>>> Here's the bisect result: > >>>>> 0519c102f5285476d7868a387bdb6c58385e4074 is the first bad commit > >>>>> commit 0519c102f5285476d7868a387bdb6c58385e4074 > >>>>> Author: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > >>>>> Date: Mon Jan 22 19:41:31 2018 +0200 > >>>>> > >>>>> drm/i915: Implement display w/a #1143 > >>>>> > >>>>> Apparently SKL/KBL/CFL need some manual help to get the > >>>>> programmed HDMI vswing to stick. Implement the relevant > >>>>> workaround (display w/a #1143). > >>>>> > >>>>> Note that the relevant chicken bits live in a transcoder register > >>>>> even though the bits affect a specific DDI port rather than a > >>>>> specific transcoder. Hence we must pick the correct transcoder > >>>>> register instance based on the port rather than based on the > >>>>> cpu_transcoder. > >>>>> > >>>>> Also note that for completeness I included support for DDI A/E > >>>>> in the code even though we never have HDMI on those ports. > >>>>> > >>>>> v2: CFL needs the w/a as well (Rodrigo and Art) > >>>>> > >>>>> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > >>>>> Cc: Art Runyan <arthur.j.runyan@xxxxxxxxx> > >>>>> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > >>>>> Link: > >>>>> https://patchwork.freedesktop.org/patch/msgid/20180122174131.28046 > >>>>> -1-ville.syrjala@xxxxxxxxxxxxxxx > >>>>> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > >>>>> > >>>>> > >>>>> dmesg from drm-tip with drm.debug=0xe can be found here: > >>>>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comme > >>>>> nts > >>>>> / > >>>>> 64 > >>>>> > >>>>> Kai-Heng > >>>> > >>>> > >>> > > > > -- > > Ville Syrjälä > > Intel -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
