Re: [PATCH v11 4/5] drm/msm/dp: parser link-frequencies as property of dp_out endpoint

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 09/12/2022 00:36, Kuogee Hsieh wrote:
Add capability to parser and retrieve max DP link supported rate from
link-frequencies property of dp_out endpoint.

Changes in v6:
-- second patch after split parser patch into two patches

Changes in v7:
-- without checking cnt against DP_MAX_NUM_DP_LANES to retrieve link rate

Changes in v9:
-- separate parser link-frequencies out of data-lanes

Changes in v10:
-- add dp_parser_link_frequencies()

Changes in v11:
-- return 0 if(!endpoint)

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
  drivers/gpu/drm/msm/dp/dp_parser.c | 27 +++++++++++++++++++++++++++
  drivers/gpu/drm/msm/dp/dp_parser.h |  2 ++
  2 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index b5f7e70..9a7dcd4 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -91,6 +91,29 @@ static int dp_parser_ctrl_res(struct dp_parser *parser)
  	return 0;
  }
+static u32 dp_parser_link_frequencies(struct device_node *of_node)
+{
+	struct device_node *endpoint;
+	u64 frequency = 0;
+	int cnt = 0;
+
+	endpoint = of_graph_get_endpoint_by_regs(of_node, 1, 0); /* port@1 */
+	if (!endpoint)
+		return 0;
+
+	cnt = of_property_count_u64_elems(endpoint, "link-frequencies");
+
+	if (cnt > 0)
+		of_property_read_u64_index(endpoint, "link-frequencies",
+						cnt - 1, &frequency);
+	of_node_put(endpoint);
+
+	frequency /= 10;	/* from symbol rate to link rate */
+	frequency /= 1000;	/* kbytes */
+
+	return frequency;
+}
+
  static int dp_parser_misc(struct dp_parser *parser)
  {
  	struct device_node *of_node = parser->pdev->dev.of_node;
@@ -113,6 +136,10 @@ static int dp_parser_misc(struct dp_parser *parser)
  			parser->max_dp_lanes = DP_MAX_NUM_DP_LANES; /* 4 lanes */
  	}
+ parser->max_dp_link_rate = dp_parser_link_frequencies(of_node);
+	if (!parser->max_dp_link_rate)
+                parser->max_dp_link_rate = DP_LINK_RATE_HBR2; /* 540000 khz */

Drop the comment please. One can jump to the defined value to see what is it equal to. So it adds no information.

+
  	return 0;
  }
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
index 866c1a8..6b10c3e 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_RATE_HBR2	540000 /* khz */

kbytes, not kHz. Otherwise it would have been 5400000.

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);

--
With best wishes
Dmitry




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux