[PATCH 4.15 032/146] drm/amd/display: Default HDMI6G support to true. Log VBIOS table error.

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Harry Wentland <harry.wentland@xxxxxxx>

commit caf0a9030d75509f3cacefe466d6d69d26e3dee6 upstream.

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@xxxxxxx>
Reviewed-by: Roman Li <Roman.Li@xxxxxxx>
Reviewed-by: Tony Cheng <Tony.Cheng@xxxxxxx>
Acked-by: Harry Wentland <harry.wentland@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c
@@ -683,6 +683,7 @@ 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;
@@ -757,15 +758,24 @@ 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);
 	}
 }