Messages in this thread Patch in this message | | | Date | Wed, 7 Dec 2022 22:13:23 +0200 | Subject | Re: [PATCH v10 4/5] drm/msm/dp: parser link-frequencies as property of dp_out endpoint | From | Dmitry Baryshkov <> |
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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
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