From: Nicholas Kazlauskas nicholas.kazlauskas@amd.com

[ Upstream commit a24eaa5c51255b344d5a321f1eeb3205f2775498 ]

[Why] Whenever we switch between tiled formats without also switching pixel formats or doing anything else that recreates the DC plane state we can run into underflow or hangs since we're not updating the DML parameters before committing to the hardware.

[How] If the update type is FULL then call validate_bandwidth again to update the DML parmeters before committing the state.

This is basically just a workaround and protective measure against update types being added DC where we could run into this issue in the future.

We can only fully validate the state in advance before applying it to the hardware if we recreate all the plane and stream states since we can't modify what's currently in use.

The next step is to update DM to ensure that we're creating the plane and stream states for whatever could potentially be a full update in DC to pre-emptively recreate the state for DC global validation.

The workaround can stay until this has been fixed in DM.

Signed-off-by: Nicholas Kazlauskas nicholas.kazlauskas@amd.com Reviewed-by: Hersen Wu hersenxs.wu@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/display/dc/core/dc.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c index 2028dc017f7a..b95a58aa82d9 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c @@ -2230,6 +2230,12 @@ void dc_commit_updates_for_stream(struct dc *dc,

copy_stream_update_to_stream(dc, context, stream, stream_update);

+ if (!dc->res_pool->funcs->validate_bandwidth(dc, context, false)) { + DC_ERROR("Mode validation failed for stream update!\n"); + dc_release_state(context); + return; + } + commit_planes_for_stream( dc, srf_updates,