From: Anthony Koo Date: Fri, 15 Feb 2019 19:19:30 +0000 (-0500) Subject: drm/amd/display: Fix soft hang issue when some DPCD data invalid X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=07d6a199219562834757ac72c28f3836b4e85694;p=android-x86%2Fkernel.git drm/amd/display: Fix soft hang issue when some DPCD data invalid [Why] AUX transaction returns success, but data has invalid lane count and rate which when passed to VBIOS command table causes it to soft hang [How] Do some sanity checking and fail if the DPCD caps are invalid. Signed-off-by: Anthony Koo Reviewed-by: Tony Cheng Acked-by: Bhawanpreet Lakha Signed-off-by: Alex Deucher --- diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c index 8ad79df56bf8..e1081e2dffdc 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c @@ -2474,6 +2474,15 @@ static bool retrieve_link_cap(struct dc_link *link) } } + /* Error condition checking... + * It is impossible for Sink to report Max Lane Count = 0. + * It is possible for Sink to report Max Link Rate = 0, if it is + * an eDP device that is reporting specialized link rates in the + * SUPPORTED_LINK_RATE table. + */ + if (dpcd_data[DP_MAX_LANE_COUNT - DP_DPCD_REV] == 0) + return false; + link->dpcd_caps.dpcd_rev.raw = dpcd_data[DP_DPCD_REV - DP_DPCD_REV];