FAILED: patch "[PATCH] drm/amd/display: Default HDMI6G support to true. Log VBIOS" failed to apply to 4.16-stable tree

[<gregkh@linuxfoundation.org>]

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);
 	}
 }