linux-kernel - [PATCH v2 2/2] drm/msm/dp: add support of max dp link rate

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Message-ID: <1668018895-29023-3-git-send-email-quic_khsieh@quicinc.com>
Date:   Wed, 9 Nov 2022 10:34:55 -0800
From:   Kuogee Hsieh <quic_khsieh@...cinc.com>
To:     <dri-devel@...ts.freedesktop.org>, <robdclark@...il.com>,
        <sean@...rly.run>, <swboyd@...omium.org>, <dianders@...omium.org>,
        <vkoul@...nel.org>, <daniel@...ll.ch>, <airlied@...ux.ie>,
        <agross@...nel.org>, <dmitry.baryshkov@...aro.org>,
        <bjorn.andersson@...aro.org>
CC:     Kuogee Hsieh <quic_khsieh@...cinc.com>,
        <quic_abhinavk@...cinc.com>, <quic_sbillaka@...cinc.com>,
        <freedreno@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 2/2] drm/msm/dp: add support of max dp link rate

Since it is not every platform supports HBR3 link rate, this patch
limit the DP link rate at max link rate if it is specified at DTS file.
Otherwise, the max dp link rate will be limited at HBR2 as before.

Changes in v2:
-- add max link rate from dtsi

Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 1 +
 drivers/gpu/drm/msm/dp/dp_panel.c   | 5 ++---
 drivers/gpu/drm/msm/dp/dp_panel.h   | 1 +
 drivers/gpu/drm/msm/dp/dp_parser.c  | 8 ++++++++
 drivers/gpu/drm/msm/dp/dp_parser.h  | 1 +
 5 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 29c9845..0e1a9b3 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -390,6 +390,7 @@ 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_dp_link_rate = dp->parser->max_dp_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 5149ceb..87c27ca 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -78,9 +78,8 @@ 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);
+	if (link_info->rate > dp_panel->max_dp_link_rate)
+		link_info->rate = dp_panel->max_dp_link_rate;
 
 	drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", major, minor);
 	drm_dbg_dp(panel->drm_dev, "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 d861197a..f04d021 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.h
+++ b/drivers/gpu/drm/msm/dp/dp_panel.h
@@ -50,6 +50,7 @@ struct dp_panel {
 
 	u32 vic;
 	u32 max_dp_lanes;
+	u32 max_dp_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 dd73221..d2e31c2 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -95,6 +95,7 @@ static int dp_parser_misc(struct dp_parser *parser)
 {
 	struct device_node *of_node = parser->pdev->dev.of_node;
 	int len;
+	u32	rate;
 
 	len = drm_of_get_data_lanes_count(of_node, 1, DP_MAX_NUM_DP_LANES);
 	if (len < 0) {
@@ -104,6 +105,13 @@ static int dp_parser_misc(struct dp_parser *parser)
 	}
 
 	parser->max_dp_lanes = len;
+
+	len = of_property_read_s32(of_node, "link-frequencies", &rate);
+	if (len >= 0)
+		parser->max_dp_link_rate = rate;
+	else
+		parser->max_dp_link_rate = 540000;	/* default HBR2 */
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
index 866c1a8..ba63375 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.h
+++ b/drivers/gpu/drm/msm/dp/dp_parser.h
@@ -119,6 +119,7 @@ struct dp_parser {
 	struct dp_io io;
 	struct dp_display_data disp_data;
 	u32 max_dp_lanes;
+	u32 max_dp_link_rate;
 	struct drm_bridge *next_bridge;
 
 	int (*parse)(struct dp_parser *parser);
-- 
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