lkml.org 
[lkml]   [2022]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [PATCH v10 4/5] drm/msm/dp: parser link-frequencies as property of dp_out endpoint
From
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@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..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

\
 
 \ /
  Last update: 2022-12-07 21:14    [W:0.091 / U:0.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site