linux-kernel - [PATCH v5 2/3] drm/msm/dp: parser data-lanes and link-frequencies from endpoint node

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Date:   Tue, 29 Nov 2022 16:12:10 -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 v5 2/3] drm/msm/dp: parser data-lanes and link-frequencies from endpoint node

Both data-lanes and link-frequencies are property of endpoint. This
patch parser endpoint to retrieve max data lanes and max link rate
supported specified at dp_out endpoint. In the case where no endpoint
specified, then 4 data lanes with HBR2 link rate (5.4G) will be the
default link configuration.

Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
---
 drivers/gpu/drm/msm/dp/dp_parser.c | 34 ++++++++++++++++++++++++++--------
 drivers/gpu/drm/msm/dp/dp_parser.h |  2 ++
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index dd73221..9367f8c 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -94,16 +94,34 @@ static int dp_parser_ctrl_res(struct dp_parser *parser)
 static int dp_parser_misc(struct dp_parser *parser)
 {
 	struct device_node *of_node = parser->pdev->dev.of_node;
-	int len;
-
-	len = drm_of_get_data_lanes_count(of_node, 1, DP_MAX_NUM_DP_LANES);
-	if (len < 0) {
-		DRM_WARN("Invalid property \"data-lanes\", default max DP lanes = %d\n",
-			 DP_MAX_NUM_DP_LANES);
-		len = DP_MAX_NUM_DP_LANES;
+	struct device_node *endpoint;
+	int cnt;
+	u64 frequence[4];
+
+	endpoint = of_graph_get_endpoint_by_regs(of_node, 1, 0); /* port@1 */
+	if (endpoint) {
+		cnt = of_property_count_u32_elems(endpoint, "data-lanes");
+		if (cnt < 0)
+			parser->max_dp_lanes = DP_MAX_NUM_DP_LANES; /* 4 lanes */
+		else
+			parser->max_dp_lanes = cnt;
+
+		cnt = of_property_count_u64_elems(endpoint, "link-frequencies");
+		if (cnt < 0) {
+			parser->max_dp_link_rate = DP_LINK_FREQUENCY_HBR2; /* 54000 khz */
+		} else {
+			if (cnt > 4)	/* 4 frequency at most */
+				cnt = 4;
+			of_property_read_u64_array(endpoint, "link-frequencies", frequence, cnt);
+			parser->max_dp_link_rate = (u32)frequence[cnt  -1];
+			parser->max_dp_link_rate /= 1000;	/* khz */
+		}
+	} else {
+		/* default */
+		parser->max_dp_lanes = DP_MAX_NUM_DP_LANES; /* 4 lanes */
+		parser->max_dp_link_rate = DP_LINK_FREQUENCY_HBR2; /* 54000 khz */
 	}
 
-	parser->max_dp_lanes = len;
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
index 866c1a8..76ddb751 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.h
+++ b/drivers/gpu/drm/msm/dp/dp_parser.h
@@ -15,6 +15,7 @@
 #define DP_LABEL "MDSS DP DISPLAY"
 #define DP_MAX_PIXEL_CLK_KHZ	675000
 #define DP_MAX_NUM_DP_LANES	4
+#define DP_LINK_FREQUENCY_HBR2	540000
 
 enum dp_pm_type {
 	DP_CORE_PM,
@@ -119,6 +120,7 @@ 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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