[PATCH 2/7] drm/amd/display: Reset plane when tiling flags change

[Kazlauskas, Nicholas]

On 2020-08-05 5:11 p.m., Rodrigo Siqueira wrote:
> On 07/30, Nicholas Kazlauskas wrote:
>> [Why]
>> Enabling or disable DCC or switching between tiled and linear formats
>> can require bandwidth updates.
>>
>> They're currently skipping all DC validation by being treated as purely
>> surface updates.
>>
>> [How]
>> Treat tiling_flag changes (which encode DCC state) as a condition for
>> resetting the plane.
>>
>> Cc: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
>> Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
>> Cc: Hersen Wu <hersenxs.wu at amd.com>
>> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
>> ---
>>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> index 7cc5ab90ce13..bf1881bd492c 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -8332,6 +8332,8 @@ static bool should_reset_plane(struct drm_atomic_state *state,
>>   	 * TODO: Come up with a more elegant solution for this.
>>   	 */
>>   	for_each_oldnew_plane_in_state(state, other, old_other_state, new_other_state, i) {
>> +		struct dm_plane_state *old_dm_plane_state, *new_dm_plane_state;
>> +
>>   		if (other->type == DRM_PLANE_TYPE_CURSOR)
>>   			continue;
>>   
>> @@ -8342,9 +8344,20 @@ static bool should_reset_plane(struct drm_atomic_state *state,
>>   		if (old_other_state->crtc != new_other_state->crtc)
>>   			return true;
>>   
>> -		/* TODO: Remove this once we can handle fast format changes. */
>> -		if (old_other_state->fb && new_other_state->fb &&
>> -		    old_other_state->fb->format != new_other_state->fb->format)
>> +		/* Framebuffer checks fall at the end. */
>> +		if (!old_other_state->fb || !new_other_state->fb)
>> +			continue;
>> +
>> +		/* Pixel format changes can require bandwidth updates. */
>> +		if (old_other_state->fb->format != new_other_state->fb->format)
>> +			return true;
>> +
>> +		old_dm_plane_state = to_dm_plane_state(old_other_state);
>> +		new_dm_plane_state = to_dm_plane_state(new_other_state);
>> +
>> +		/* Tiling and DCC changes also require bandwidth updates. */
>> +		if (old_dm_plane_state->tiling_flags !=
>> +		    new_dm_plane_state->tiling_flags)
> 
> Why not add a case when we move to a TMZ area?
> 
> Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>

TMZ doesn't affect DML calculations or validation in this case so we can 
safely skip it.

Regards,
Nicholas Kazlauskas

> 
>>   			return true;
>>   	}
>>   
>> -- 
>> 2.25.1
>>
>