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Message-ID: <0bd08349-d6ec-bec4-e1bd-6f98d1af5968@quicinc.com>
Date: Tue, 29 Nov 2022 16:08:35 -0800
From: Kuogee Hsieh <quic_khsieh@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
<dri-devel@...ts.freedesktop.org>, <robdclark@...il.com>,
<sean@...rly.run>, <swboyd@...omium.org>, <dianders@...omium.org>,
<vkoul@...nel.org>, <daniel@...ll.ch>, <agross@...nel.org>
CC: <quic_abhinavk@...cinc.com>, <quic_sbillaka@...cinc.com>,
<freedreno@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] drm/msm/dp: add support of max dp link rate
On 11/18/2022 3:04 AM, Dmitry Baryshkov wrote:
> On 18/11/2022 01:49, Kuogee Hsieh wrote:
>> dp_out endpoint contains both data-lanes and link-frequencies
>> properties.
>> This patch parser dp_out endpoint properties and acquire dp_max_lanes
>> and
>> dp_max_link_rate from respective property. Finally, comparing them
>> against
>> both data lane and link rate read back from sink to ensure both data
>> lane
>> and link rate are supported by platform.
>> In the case there is no data-lanes or link-frequencies property
>> defined at
>> dp_out endpoint, the default value are 4 data lanes with 5.4 Ghz link
>> rate.
>>
>> Changes in v2:
>> -- add max link rate from dtsi
>>
>> Changes in v3:
>> -- parser max_data_lanes and max_dp_link_rate from dp_out endpoint
>>
>> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
>> ---
>> arch/arm64/boot/dts/qcom/sc7280.dtsi | 1 +
>
> Should not be a part of this patch.
>
>> drivers/gpu/drm/msm/dp/dp_display.c | 4 ++++
>> drivers/gpu/drm/msm/dp/dp_panel.c | 7 ++++---
>> drivers/gpu/drm/msm/dp/dp_panel.h | 1 +
>> drivers/gpu/drm/msm/dp/dp_parser.c | 30
>> ++++++++++++++++++++++--------
>> drivers/gpu/drm/msm/dp/dp_parser.h | 2 ++
>> 6 files changed, 34 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> index 4afe53b..d456e76 100644
>> --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>> @@ -3897,6 +3897,7 @@
>> reg = <0>;
>> dp_in: endpoint {
>> remote-endpoint = <&dpu_intf0_out>;
>> + data-lanes = <0 1 2 3>;
>> };
>> };
>> };
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
>> b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 29c9845..4fe2092 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -390,6 +390,10 @@ static int dp_display_process_hpd_high(struct
>> dp_display_private *dp)
>> struct edid *edid;
>> dp->panel->max_dp_lanes = dp->parser->max_dp_lanes;
>> + dp->panel->max_dp_link_rate = dp->parser->max_dp_link_rate;
>> +
>> + drm_dbg_dp(dp->drm_dev, "max_lanes=%d max_link_rate=%d\n",
>> + dp->panel->max_dp_lanes, dp->panel->max_dp_link_rate);
>> rc = dp_panel_read_sink_caps(dp->panel,
>> dp->dp_display.connector);
>> if (rc)
>> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c
>> b/drivers/gpu/drm/msm/dp/dp_panel.c
>> index 5149ceb..933fa9c 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
>> @@ -75,12 +75,13 @@ static int dp_panel_read_dpcd(struct dp_panel
>> *dp_panel)
>> link_info->rate =
>> drm_dp_bw_code_to_link_rate(dpcd[DP_MAX_LINK_RATE]);
>> link_info->num_lanes = dpcd[DP_MAX_LANE_COUNT] &
>> DP_MAX_LANE_COUNT_MASK;
>> + /* Limit data lanes from data-lanes of endpoint properity of
>> dtsi */
>> if (link_info->num_lanes > dp_panel->max_dp_lanes)
>> link_info->num_lanes = dp_panel->max_dp_lanes;
>> - /* Limit support upto HBR2 until HBR3 support is added */
>> - if (link_info->rate >=
>> (drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4)))
>> - link_info->rate = drm_dp_bw_code_to_link_rate(DP_LINK_BW_5_4);
>> + /* Limit link rate from link-frequencies of endpoint properity
>> of dtsi */
>> + if (link_info->rate > dp_panel->max_dp_link_rate)
>> + link_info->rate = dp_panel->max_dp_link_rate;
>> drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", major, minor);
>> drm_dbg_dp(panel->drm_dev, "link_rate=%d\n", link_info->rate);
>> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h
>> b/drivers/gpu/drm/msm/dp/dp_panel.h
>> index d861197a..f04d021 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_panel.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_panel.h
>> @@ -50,6 +50,7 @@ struct dp_panel {
>> u32 vic;
>> u32 max_dp_lanes;
>> + u32 max_dp_link_rate;
>> u32 max_bw_code;
>> };
>> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c
>> b/drivers/gpu/drm/msm/dp/dp_parser.c
>> index dd73221..667981e 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
>> @@ -94,16 +94,30 @@ 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;
>> - int len;
>> -
>> - len = drm_of_get_data_lanes_count(of_node, 1, DP_MAX_NUM_DP_LANES);
>> - if (len < 0) {
>> - DRM_WARN("Invalid property \"data-lanes\", default max DP
>> lanes = %d\n",
>> - DP_MAX_NUM_DP_LANES);
>> - len = DP_MAX_NUM_DP_LANES;
>> + struct device_node *endpoint;
>> + int cnt;
>> + u32 frequence = 0;
>> +
>> + endpoint = of_graph_get_endpoint_by_regs(of_node, 1, 0);
>> +
>> + if (endpoint) {
>> + cnt = of_property_count_u32_elems(endpoint, "data-lanes");
>> + if (cnt < 0)
>> + parser->max_dp_lanes = DP_MAX_NUM_DP_LANES; /* 4 lanes */
>> + else
>> + parser->max_dp_lanes = cnt;
>
> This should be a separate patch. And now what,
> drm_of_get_data_lanes_count() can be used here too. Why are you
> dropping the generic function for the sake of your custom implementatoin.
drm_of_get_data_lanes_count() expect the parent node of endpoint.
It will locate endpoint first and call of_property_count_u32_elems() to
retrieve count of elements and there is no similar function for
link-frequencies.
To get link-frequencies we have to locate endpoint already. so why not
use same endpoint for both data-lanes and link-frequencies.
So that consistent way are used to retrieve both data-lanes and
link-frequencies.
>
>> +
>> + cnt = of_property_count_u32_elems(endpoint,
>> "link-frequencies");
>> + if (cnt < 0) {
>> + parser->max_dp_link_rate = DP_LINK_FREQUENCY_HBR2; /*
>> 54000 khz */
>> + } else {
>> + of_property_read_u32_array(endpoint, "link-frequencies",
>> &frequence, 1);
>
> link-frequencies is u64 array.
>
>> + parser->max_dp_link_rate = frequence;
>> + }
>> }
>> - parser->max_dp_lanes = len;
>> + pr_err("%s: kuogee, lane=%d frequency=%d\n", __func__,
>> parser->max_dp_lanes, parser->max_dp_link_rate);
>> +
>
> Leftover?
>
>> return 0;
>> }
>> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h
>> b/drivers/gpu/drm/msm/dp/dp_parser.h
>> index 866c1a8..76ddb751 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_FREQUENCY_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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