From 92a6ea98405ccb7b2c47b2480a1e43bbc7e5d1a1 Mon Sep 17 00:00:00 2001 From: abdoulaye berthe Date: Wed, 18 Sep 2019 11:57:47 -0400 Subject: [PATCH 4396/4736] drm/amd/display: check for dp rev before reading lttpr regs [Why] LTTPR was introduced after DP1.2. Reading LTTPR registers 0xFXXXX on some DP 1.2 display is causing an unexpected behavior. [How] Make sure that we don't read any lttpr registers on 1.2 displays. Signed-off-by: abdoulaye berthe Reviewed-by: Aric Cyr --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 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 2a89f90ef7a7..1e4480f3bd3c 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 @@ -2759,9 +2759,10 @@ static bool retrieve_link_cap(struct dc_link *link) /* Set default timeout to 3.2ms and read LTTPR capabilities */ bool ext_timeout_support = link->dc->caps.extended_aux_timeout_support && !link->dc->config.disable_extended_timeout_support; + link->is_lttpr_mode_transparent = true; + if (ext_timeout_support) { status = dc_link_aux_configure_timeout(link->ddc, LINK_AUX_DEFAULT_EXTENDED_TIMEOUT_PERIOD); - link->is_lttpr_mode_transparent = true; } memset(dpcd_data, '\0', sizeof(dpcd_data)); @@ -2796,7 +2797,7 @@ static bool retrieve_link_cap(struct dc_link *link) return false; } - if (ext_timeout_support) { + if (ext_timeout_support && link->dpcd_caps.dpcd_rev.raw >= 0x14) { status = core_link_read_dpcd( link, DP_PHY_REPEATER_CNT, -- 2.17.1