[PATCH v8 4/5] drm/msm/dp: parser link-frequencies as property of dp_out endpoint

From: Kuogee Hsieh
Date: Mon Dec 05 2022 - 14:16:45 EST


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

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/dp/dp_parser.c | 19 +++++++++++++++++--
drivers/gpu/drm/msm/dp/dp_parser.h | 2 ++
2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index b5f7e70..037dad8 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -94,15 +94,28 @@ 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;
+ struct device_node *endpoint;
+ u64 frequency;
int cnt;

/*
* data-lanes is the property of dp_out endpoint
*/
cnt = drm_of_get_data_lanes_count_ep(of_node, 1, 0, 1, DP_MAX_NUM_DP_LANES);
- if (cnt > 0)
+ if (cnt > 0) {
parser->max_dp_lanes = cnt;
- else {
+
+ endpoint = of_graph_get_endpoint_by_regs(of_node, 1, 0); /* port@1 */
+ 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 */
+ parser->max_dp_link_rate = (frequency / 1000); /* kbits */
+ } else {
+ parser->max_dp_link_rate = DP_LINK_RATE_HBR2; /* 540000 khz */
+ }
+ } else {
/*
* legacy code, data-lanes is the property of mdss_dp node
*/
@@ -111,6 +124,8 @@ static int dp_parser_misc(struct dp_parser *parser)
parser->max_dp_lanes = cnt;
else
parser->max_dp_lanes = DP_MAX_NUM_DP_LANES; /* 4 lanes */
+
+ 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..3ddf639 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

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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