On 01/12/2022 01:51, 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
Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/dp/dp_parser.c | 16 ++++++++++++++++
drivers/gpu/drm/msm/dp/dp_parser.h | 2 ++
2 files changed, 18 insertions(+)
diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index b06ff60..2006341 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -95,6 +95,7 @@ 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;
/*
@@ -103,6 +104,7 @@ static int dp_parser_misc(struct dp_parser *parser)
cnt = drm_of_get_data_lanes_count(of_node, 1, DP_MAX_NUM_DP_LANES);
if (cnt > 0) {
parser->max_dp_lanes = cnt;
+ parser->max_dp_link_rate = DP_LINK_RATE_HBR2; /* 540000 khz */
return 0;
}
@@ -116,8 +118,22 @@ static int dp_parser_misc(struct dp_parser *parser)
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_RATE_HBR2; /* 540000 khz */
+ } else {
+ if (cnt > DP_MAX_NUM_DP_LANES)
+ cnt = DP_MAX_NUM_DP_LANES;
Why are you comparing the number of link frequencies with the number of
lanes? You don't need the comparison at all.
+
+ of_property_read_u64_index(endpoint, "link-frequencies",
+ cnt - 1, &frequency);
Checking of the return value?
+
+ parser->max_dp_link_rate = (frequency / 1000); /* kbits */
+ }
} else {
parser->max_dp_lanes = DP_MAX_NUM_DP_LANES; /* 4 lanes */
+ parser->max_dp_link_rate = DP_LINK_RATE_HBR2; /* 540000 khz */
Instead of having all the nested if's and setting of max_dp_link rate in
several branches, please add a function that returns either a valid rate
or an error. Then you can simply check the result of that function and
set the default.
}
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);
--
With best wishes
Dmitry
