[PATCH v2 2/2] drm/msm/dp: add supported max link rate specified from dtsi

[Kuogee Hsieh]

Allow supported link rate to be limited to the value specified at
dtsi. If it is not specified, then link rate is derived from dpcd
directly. Below are examples,
link-rate = <162000> for max link rate limited at 1.62G
link-rate = <270000> for max link rate limited at 2.7G
link-rate = <540000> for max link rate limited at 5.4G
link-rate = <810000> for max link rate limited at 8.1G

Changes in V2:
-- allow supported max link rate specified from dtsi

Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/dp/dp_display.c |  1 +
 drivers/gpu/drm/msm/dp/dp_panel.c   |  7 ++++---
 drivers/gpu/drm/msm/dp/dp_panel.h   |  1 +
 drivers/gpu/drm/msm/dp/dp_parser.c  | 13 +++++++++++++
 drivers/gpu/drm/msm/dp/dp_parser.h  |  1 +
 5 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 5a39da6..f633ba6 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -322,6 +322,7 @@ static int dp_display_process_hpd_high(struct dp_display_private *dp)
 	struct edid *edid;
 
 	dp->panel->max_dp_lanes = dp->parser->max_dp_lanes;
+	dp->panel->max_link_rate = dp->parser->max_link_rate;
 
 	rc = dp_panel_read_sink_caps(dp->panel, dp->dp_display.connector);
 	if (rc)
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
index 9cc8166..be7f102 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -76,9 +76,10 @@ static int dp_panel_read_dpcd(struct dp_panel *dp_panel)
 	if (link_info->num_lanes > dp_panel->max_dp_lanes)
 		link_info->num_lanes = dp_panel->max_dp_lanes;
 
-	/* Limit support upto HBR2 until HBR3 support is added */
-	if (link_info->rate >= (drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4)))
-		link_info->rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4);
+	/* Limit support of ink rate if specified */
+	if (dp_panel->max_link_rate &&
+			(link_info->rate > dp_panel->max_link_rate))
+		link_info->rate = dp_panel->max_link_rate;
 
 	DRM_DEBUG_DP("version: %d.%d\n", major, minor);
 	DRM_DEBUG_DP("link_rate=%d\n", link_info->rate);
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
index 9023e5b..1876f5e 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.h
+++ b/drivers/gpu/drm/msm/dp/dp_panel.h
@@ -51,6 +51,7 @@ struct dp_panel {
 	u32 vic;
 	u32 max_pclk_khz;
 	u32 max_dp_lanes;
+	u32 max_link_rate;
 
 	u32 max_bw_code;
 };
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index 0519dd3..d8b6898 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -87,6 +87,8 @@ static int dp_parser_misc(struct dp_parser *parser)
 	struct device_node *of_node = parser->pdev->dev.of_node;
 	int len = 0;
 	const char *data_lane_property = "data-lanes";
+	const char *link_rate_property = "link-rate";
+	u32 rate = 0;
 
 	len = of_property_count_elems_of_size(of_node,
 			 data_lane_property, sizeof(u32));
@@ -97,6 +99,17 @@ static int dp_parser_misc(struct dp_parser *parser)
 	}
 
 	parser->max_dp_lanes = len;
+
+	len = of_property_count_elems_of_size(of_node,
+			 link_rate_property, sizeof(u32));
+
+	if (len == 1) {
+		of_property_read_u32_index(of_node,
+				link_rate_property, 0, &rate);
+
+		parser->max_link_rate = rate;
+	}
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
index 34b4962..7046fce 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.h
+++ b/drivers/gpu/drm/msm/dp/dp_parser.h
@@ -116,6 +116,7 @@ struct dp_parser {
 	struct dp_display_data disp_data;
 	const struct dp_regulator_cfg *regulator_cfg;
 	u32 max_dp_lanes;
+	u32 max_link_rate;
 
 	int (*parse)(struct dp_parser *parser);
 };
-- 
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