On 07/12/2022 18:57, 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()
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..9398abe 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -91,6 +91,28 @@ 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 -ENODEV; (or 0, as you have u32)
It's much easier IMO.
+ if (endpoint)
+ cnt = of_property_count_u64_elems(endpoint, "link-frequencies");
+
+ if (cnt > 0) {
+ of_property_read_u64_index(endpoint, "link-frequencies",
+ cnt - 1, &frequency);
+ frequency /= 10; /* from symbol rate to link rate */
+ frequency /= 1000; /* kbits */
kbytes?
+ }
+
+ of_node_put(endpoint);
Even easier:
cnt = of_property_count(...);
if (cnt > 0)
of_property_read_u64_index(...);
of_node_put(endpoint);
frequency /= 10;
frequency /= 1000;
return frequency;
+
+ return (u32)frequency;
+}
+
static int dp_parser_misc(struct dp_parser *parser)
{
struct device_node *of_node = parser->pdev->dev.of_node;
@@ -113,6 +135,11 @@ 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);
+
Drop the empty line please. The if checks the result of the previous
assignment. It's easier to comprehend if they visually belong to the
same code block.
+ if (!parser->max_dp_link_rate)
+ parser->max_dp_link_rate = DP_LINK_RATE_HBR2; /* 540000 khz */
+
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 */
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
