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)

Changes in v12:
-- replace khz with kbytes at dp_parser.h

Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
---
 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..5549495 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;
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
index 866c1a8..526131ee 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 /* kbytes */
 
 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);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Quoting Kuogee Hsieh (2022-12-13 13:44:07)
> Add capability to parser and retrieve max DP link supported rate from

to parse

> 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)
>
> Changes in v12:
> -- replace khz with kbytes at dp_parser.h
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---

Same parser in subject.

>  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..5549495 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;

'cnt' doesn't need to be initialized here.

> +
> +       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 */

Use do_div(frequency, 10 * 1000)? If you want comments it could maybe be
like this:

	do_div(frequency,
	       10 * /* from symbol rate to link rate */
	       1000); /* kbytes */

> +
> +       return frequency;
> +}
> +

On 13 December 2022 23:44:07 EET, Kuogee Hsieh <quic_khsieh@quicinc.com> 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)
>
>Changes in v12:
>-- replace khz with kbytes at dp_parser.h
>
>Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>


Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


>---
> drivers/gpu/drm/msm/dp/dp_parser.c | 27 +++++++++++++++++++++++++++
> drivers/gpu/drm/msm/dp/dp_parser.h |  2 ++
> 2 files changed, 29 insertions(+)


-- 
With best wishes
Dmitry