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 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 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
