From aa030c7b66c1ea84ed86779ca7891b86b1616eb8 Mon Sep 17 00:00:00 2001 From: "Leo (Sunpeng) Li" Date: Tue, 26 Jun 2018 10:50:16 -0400 Subject: [PATCH 4929/5725] 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 --- drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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 d108ccf..08c9d73 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); -- 2.7.4