[Intel-gfx] [Regression] "drm/i915: Implement display w/a #1143" breaks HDMI on ASUS GL552VW

Kai-Heng Feng kai.heng.feng at canonical.com
Tue Oct 13 12:18:17 UTC 2020 


> On Oct 13, 2020, at 19:50, Saarinen, Jani <jani.saarinen at intel.com> wrote:
> 
> Hi, 
>> -----Original Message-----
>> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Ville
>> Syrjälä
>> Sent: tiistai 13. lokakuuta 2020 14.16
>> To: Kai-Heng Feng <kai.heng.feng at canonical.com>
>> Cc: intel-gfx <intel-gfx at lists.freedesktop.org>; Runyan, Arthur J
>> <arthur.j.runyan at intel.com>
>> Subject: Re: [Intel-gfx] [Regression] "drm/i915: Implement display w/a #1143"
>> breaks HDMI on ASUS GL552VW
>> 
>> On Tue, Oct 13, 2020 at 01:20:35PM +0800, Kai-Heng Feng wrote:
>>> 
>>> 
>>>> On Sep 3, 2020, at 14:26, Kai-Heng Feng <kai.heng.feng at canonical.com>
>> wrote:
>>>> 
>>>> 
>>>> 
>>>>> On Aug 26, 2020, at 21:05, Ville Syrjälä <ville.syrjala at linux.intel.com>
>> wrote:
>>>>> 
>>>>> 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 at intel.com> 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/comme
>>>>>> nts/119 [2]
>>>>>> 
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comme
>>>>>> nts/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.
>>>> 
>>>> 
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comment
>>>> s/124
>>>> 
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comment
>>>> s/125
>>>> 
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871721/comment
>>>> s/126
>>> 
>>> A gentle ping...
>> 
>> I cooked up some hacks for you to try:
>> git://github.com/vsyrjala/linux.git skl_vswing_wa_hacks
>> 
>> An upstream bug report would probably be a good idea so that the
>> communication doesn't have to go through a middle man over email...
> Agree, please make gitlab issue on this. 

It was filed two months ago:
https://gitlab.freedesktop.org/drm/intel/-/issues/2181


> 
>> 
>>> 
>>>> 
>>>> Kai-Heng
>>>> 
>>>>> 
>>>>>> 
>>>>>> Kai-Heng
>>>>>> 
>>>>>>> 
>>>>>>> -----Original Message-----
>>>>>>> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>>>>>>> Sent: Monday, August 24, 2020 11:05 AM
>>>>>>> To: Kai-Heng Feng <kai.heng.feng at canonical.com>
>>>>>>> Cc: Runyan, Arthur J <arthur.j.runyan at intel.com>; Vivi, Rodrigo
>>>>>>> <rodrigo.vivi at intel.com>; intel-gfx
>>>>>>> <intel-gfx at lists.freedesktop.org>
>>>>>>> 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 at intel.com> 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 at canonical.com>
>>>>>>>>> Sent: Thursday, August 13, 2020 10:14 PM
>>>>>>>>> To: Runyan, Arthur J <arthur.j.runyan at intel.com>
>>>>>>>>> Cc: Vivi, Rodrigo <rodrigo.vivi at intel.com>; Ville Syrjälä
>>>>>>>>> <ville.syrjala at linux.intel.com>; intel-gfx
>>>>>>>>> <intel-gfx at lists.freedesktop.org>
>>>>>>>>> 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 at intel.com> 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 at intel.com>
>>>>>>>>>> Sent: Thursday, August 13, 2020 9:50 AM
>>>>>>>>>> To: Kai-Heng Feng <kai.heng.feng at canonical.com>; Runyan,
>>>>>>>>>> Arthur J <arthur.j.runyan at intel.com>
>>>>>>>>>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>; intel-gfx
>>>>>>>>>> <intel-gfx at lists.freedesktop.org>
>>>>>>>>>> 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 at canonical.com> 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 at linux.intel.com>
>>>>>>>>>>> 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 at intel.com>
>>>>>>>>>>> Cc: Art Runyan <arthur.j.runyan at intel.com>
>>>>>>>>>>> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>>>>>>>>>>> Link:
>>>>>>>>>>> 
>> https://patchwork.freedesktop.org/patch/msgid/20180122174131.
>>>>>>>>>>> 28046 -1-ville.syrjala at linux.intel.com
>>>>>>>>>>> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 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
>>>> 
>> 
>> --
>> Ville Syrjälä
>> Intel
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

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