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

[Melissa Wen]

On 17-07-2025 15:55, Melissa Wen wrote:
> 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.
^ there is no single message on Desktop mode on unplug of external
display.

> 
> 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);
>>>   }
>>>