From: Leo (Sunpeng) Li Date: Tue, 26 Jun 2018 14:50:16 +0000 (-0400) Subject: drm/amd/display: Read AUX channel even if only status byte is returned X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=edf6ffe4f47e6749cfd45c1489feea2dbb0041c7;p=linux.git drm/amd/display: Read AUX channel even if only status byte is returned [Why] get_channel_status() can return 0 in returned_bytes, and report a successful operation result. This is because it prunes the first status byte out. This was preventing read_channel_reply() from being called (due to the faulty condition), and consequently preventing the AUX reply status from being set. [How] Fix the conditional so that it accounts for when get_channel_status() returns 0 bytes read. [Fixes] Fixes possible edid read failures during S3 resume, where we are now relying on DRM's DP AUX handling. This was an regression introduced by: Author: Harry Wentland drm/amd/display: Return aux replies directly to DRM Signed-off-by: Leo (Sunpeng) Li Reviewed-by: Harry Wentland Signed-off-by: Alex Deucher --- diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c index d108ccfc5cf9f..08c9d73b9ab72 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c @@ -671,7 +671,7 @@ int dc_link_aux_transfer(struct ddc_service *ddc, case AUX_CHANNEL_OPERATION_SUCCEEDED: res = returned_bytes; - if (res <= size && res > 0) + if (res <= size && res >= 0) res = engine->funcs->read_channel_reply(engine, size, buffer, reply, &status);