From: Josip Pavic <[email protected]> [Why] If no free pipes are available, acquire_first_split_pipe is called to get a pipe to use. This call may alter the ordering of the pipes in the list so that, for example, the tail pipe changes.
If acquire_first_split_pipe returns the tail pipe, we'll have free_pipe == tail_pipe. What tail_pipe refers to is not the current tail_pipe, but what was previously the tail pipe - i.e. prior to the call to acquire_first_split_pipe The logic that follows will link free_pipe to the tail pipe, referring to the current tail pipe. However, since tail_pipe is cached from before the call to acquire_first_split_pipe, the wrong tail pipe will be used, and it will end up being linked to itself, creating a loop that, if traversed, will result in a soft hang. [How] Do not cache the tail pipe. Instead, check the tail pipe after the call to acquire_first_split_pipe is made. Signed-off-by: Josip Pavic <[email protected]> Reviewed-by: Aric Cyr <[email protected]> Acked-by: Rodrigo Siqueira <[email protected]> --- drivers/gpu/drm/amd/display/dc/core/dc_resource.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c index f4bcc71b2920..7b32a34908c8 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c @@ -1358,9 +1358,6 @@ bool dc_add_plane_to_context( dc_plane_state_retain(plane_state); while (head_pipe) { - tail_pipe = resource_get_tail_pipe(&context->res_ctx, head_pipe); - ASSERT(tail_pipe); - free_pipe = acquire_free_pipe_for_head(context, pool, head_pipe); #if defined(CONFIG_DRM_AMD_DC_DCN) @@ -1378,6 +1375,8 @@ bool dc_add_plane_to_context( free_pipe->plane_state = plane_state; if (head_pipe != free_pipe) { + tail_pipe = resource_get_tail_pipe(&context->res_ctx, head_pipe); + ASSERT(tail_pipe); free_pipe->stream_res.tg = tail_pipe->stream_res.tg; free_pipe->stream_res.abm = tail_pipe->stream_res.abm; free_pipe->stream_res.opp = tail_pipe->stream_res.opp; -- 2.26.0 _______________________________________________ amd-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/amd-gfx
