The patch below does not apply to the 4.16-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ea74e15fb547483f9f86088443f2d3c9f518de8b Mon Sep 17 00:00:00 2001

From: Harry Wentland harry.wentland@amd.com Date: Tue, 20 Feb 2018 13:36:23 -0500 Subject: [PATCH] drm/amd/display: Default HDMI6G support to true. Log VBIOS table error.

There have been many reports of Ellesmere and Baffin systems not being able to drive HDMI 4k60 due to the fact that we check the HDMI_6GB_EN bit from VBIOS table. Windows seems to not have this issue.

On some systems we fail to the encoder cap info from VBIOS. In that case we should default to enabling HDMI6G support.

This was tested by dwagner on https://bugs.freedesktop.org/show_bug.cgi?id=102820

Signed-off-by: Harry Wentland harry.wentland@amd.com Reviewed-by: Roman Li Roman.Li@amd.com Reviewed-by: Tony Cheng Tony.Cheng@amd.com Acked-by: Harry Wentland harry.wentland@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c index f0d63ac7724a..81776e4797ed 100644 --- a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c @@ -678,6 +678,7 @@ void dce110_link_encoder_construct( { struct bp_encoder_cap_info bp_cap_info = {0}; const struct dc_vbios_funcs *bp_funcs = init_data->ctx->dc_bios->funcs; + enum bp_result result = BP_RESULT_OK;

enc110->base.funcs = &dce110_lnk_enc_funcs; enc110->base.ctx = init_data->ctx; @@ -752,15 +753,24 @@ void dce110_link_encoder_construct( enc110->base.preferred_engine = ENGINE_ID_UNKNOWN; }

+ /* default to one to mirror Windows behavior */ + enc110->base.features.flags.bits.HDMI_6GB_EN = 1; + + result = bp_funcs->get_encoder_cap_info(enc110->base.ctx->dc_bios, + enc110->base.id, &bp_cap_info); + /* Override features with DCE-specific values */ - if (BP_RESULT_OK == bp_funcs->get_encoder_cap_info( - enc110->base.ctx->dc_bios, enc110->base.id, - &bp_cap_info)) { + if (BP_RESULT_OK == result) { enc110->base.features.flags.bits.IS_HBR2_CAPABLE = bp_cap_info.DP_HBR2_EN; enc110->base.features.flags.bits.IS_HBR3_CAPABLE = bp_cap_info.DP_HBR3_EN; enc110->base.features.flags.bits.HDMI_6GB_EN = bp_cap_info.HDMI_6GB_EN; + } else { + dm_logger_write(enc110->base.ctx->logger, LOG_WARNING, + "%s: Failed to get encoder_cap_info from VBIOS with error code %d!\n", + __func__, + result); } }