[PATCH] Revert "drm/amd/display: limit clear_update_flags to dcn32 and above"

[Melissa Wen]

On 17-07-2025 13:39, Limonciello, Mario wrote:
> On 7/17/25 9:36 AM, Melissa Wen wrote:
>> This reverts commit e1bd5e0bb4ca0d633ad698abd3658f8265009b81.
>> 
>> The commit causes a regression in Steam Deck (DCN 3.01), reintroducing a
>> functional issue reported in [1] that was fixed by calling the
>> clear_update_flags() from commit 7671f62c10f2a.
>> 
>> On Steam Deck, we use multiple hw plane color caps and up to two overlay
>> planes with dynamic pipe split policy. I.e. with 1 primary + 1 overlay,
>> the driver split planes into two (with 4 pipes), but with 1 primary + 2
>> overlays, we don't have enough pipe for splitting. Glitches appear in
>> this pipe-split transition of 1-2 overlay planes, if the driver doesn't
>> clear update flags.
>> 
>> Besides that, the issue the commit e1bd5e0bb4ca tries to address [2]
>> isn't functional.
>> 
>> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3441 [1]
>> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/4129 [2]
>> Signed-off-by: Melissa Wen <mwen at igalia.com>
> 
> Can you please double check the use case that prompted 
> e1bd5e0bb4ca0d633ad698abd3658f8265009b81 in the first place?  IE With 
> this revert you proposed do you see a traceback on unplug of external 
> display?

Hi Mario,

I don't see either traceback or REG_WAIT timeout when unplugging an
external HDMI-connected display.
I tried with the Deck Dock and USB-C to HDMI adapter. Not sure if there
is a very specific scenario that triggers this that I didn't cover.

The only message on dmesg from this action is:
amdgpu 0000:04:00.0: amdgpu: pp_od_clk_voltage is not accessible if
power_dpm_force_performance_level is not in manual mode!

Moreover, if I move to the Desktop mode (KDE), there is no message.

Melissa

> 
>> ---
>>   drivers/gpu/drm/amd/display/dc/core/dc.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
>> index c31f7f8e409f..7c48f72e5917 100644
>> --- a/drivers/gpu/drm/amd/display/dc/core/dc.c
>> +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
>> @@ -5443,7 +5443,8 @@ bool dc_update_planes_and_stream(struct dc *dc,
>>   	else
>>   		ret = update_planes_and_stream_v2(dc, srf_updates,
>>   			surface_count, stream, stream_update);
>> -	if (ret && dc->ctx->dce_version >= DCN_VERSION_3_2)
>> +
>> +	if (ret)
>>   		clear_update_flags(srf_updates, surface_count, stream);
>>   
>>   	return ret;
>> @@ -5474,7 +5475,7 @@ void dc_commit_updates_for_stream(struct dc *dc,
>>   		ret = update_planes_and_stream_v1(dc, srf_updates, surface_count, stream,
>>   				stream_update, state);
>>   
>> -	if (ret && dc->ctx->dce_version >= DCN_VERSION_3_2)
>> +	if (ret)
>>   		clear_update_flags(srf_updates, surface_count, stream);
>>   }
>>