From b22141c0736ee943fc013f0f90a14c830875f192 Mon Sep 17 00:00:00 2001 From: Xiaodong Yan Date: Wed, 24 Oct 2018 02:08:53 +0800 Subject: [PATCH 0806/2940] drm/amd/display: retry 3 times before successfully reading DPCD Extended Receiver Capability Field [Why] 1.dpcd extended receiver capability sometimes read fail, and corrupted data leads to sink caps is not correct. 2.sometimes sink reply ack with fewer data [How] check the return value of core_link_read_dpcd, try to read again when failure happens Signed-off-by: Xiaodong Yan Reviewed-by: Wenjing Liu Acked-by: Bhawanpreet Lakha Acked-by: Tony Cheng Signed-off-by: Alex Deucher --- .../gpu/drm/amd/display/dc/core/dc_link_dp.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) 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 d91df5ef0cb3..4d1f8ac069c1 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 @@ -2371,11 +2371,22 @@ static bool retrieve_link_cap(struct dc_link *link) dpcd_data[DP_TRAINING_AUX_RD_INTERVAL]; if (aux_rd_interval.bits.EXT_RECIEVER_CAP_FIELD_PRESENT == 1) { - core_link_read_dpcd( + uint8_t ext_cap_data[16]; + + memset(ext_cap_data, '\0', sizeof(ext_cap_data)); + for (i = 0; i < read_dpcd_retry_cnt; i++) { + status = core_link_read_dpcd( link, DP_DP13_DPCD_REV, - dpcd_data, - sizeof(dpcd_data)); + ext_cap_data, + sizeof(ext_cap_data)); + if (status == DC_OK) { + memcpy(dpcd_data, ext_cap_data, sizeof(dpcd_data)); + break; + } + } + if (status != DC_OK) + dm_error("%s: Read extend caps data failed, use cap from dpcd 0.\n", __func__); } } -- 2.17.1