From: Nicholas Kazlauskas nicholas.kazlauskas@amd.com
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 shenshih@amd.com Acked-by: Anson Jacob Anson.Jacob@amd.com Tested-by: Daniel Wheeler daniel.wheeler@amd.com Signed-off-by: Nicholas Kazlauskas nicholas.kazlauskas@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ---- 1 file changed, 4 deletions(-)
--- 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_dev 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_dev } } drm_connector_list_iter_end(&iter); - drm_modeset_unlock(&dev->mode_config.connection_mutex);
}