From: Nicholas Kazlauskas Date: Thu, 4 Nov 2021 20:52:06 +0000 (-0400) Subject: drm/amd/display: Don't lock connection_mutex for DMUB HPD X-Git-Tag: v5.15.73~1913 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=760fe32034931a8c97c773edef2f1b7c7346f43a;p=platform%2Fkernel%2Flinux-rpi.git drm/amd/display: Don't lock connection_mutex for DMUB HPD commit d82b3266ef88dc10fe0e7031b2bd8ba7eedb7e59 upstream. [Why] Per DRM spec we only need to hold that lock when touching connector->state - which we do not do in that handler. Taking this locking introduces unnecessary dependencies with other threads which is bad for performance and opens up the potential for a deadlock since there are multiple locks being held at once. [How] Remove the connection_mutex lock/unlock routine and just iterate over the drm connectors normally. The iter helpers implicitly lock the connection list so this is safe to do. DC link access also does not need to be guarded since the link table is static at creation - we don't dynamically add or remove links, just streams. Fixes: e27c41d5b068 ("drm/amd/display: Support for DMUB HPD interrupt handling") Reviewed-by: Jude Shih Acked-by: Anson Jacob Tested-by: Daniel Wheeler Signed-off-by: Nicholas Kazlauskas Signed-off-by: Alex Deucher Signed-off-by: Greg Kroah-Hartman --- 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 3b4449b..2b5e8de 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -668,10 +668,7 @@ void dmub_hpd_callback(struct amdgpu_device *adev, struct dmub_notification *not return; } - drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); - link_index = notify->link_index; - link = adev->dm.dc->links[link_index]; drm_connector_list_iter_begin(dev, &iter); @@ -684,7 +681,6 @@ void dmub_hpd_callback(struct amdgpu_device *adev, struct dmub_notification *not } } drm_connector_list_iter_end(&iter); - drm_modeset_unlock(&dev->mode_config.connection_mutex); }