Re: [RFC PATCH v2 2/5] drm/msm/dp: support attaching bridges to the DP encoder

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: Kuogee Hsieh <quic_khsieh@quicinc.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
	Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Stephen Boyd <swboyd@chromium.org>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org
Subject: Re: [RFC PATCH v2 2/5] drm/msm/dp: support attaching bridges to the DP encoder
Date: Sat, 19 Feb 2022 00:31:02 +0300	[thread overview]
Message-ID: <067554a1-4def-674d-137f-b13bed6ac810@linaro.org> (raw)
In-Reply-To: <013284ad-11c7-e21c-3ca4-0e8b7b804b98@quicinc.com>

On 19/02/2022 00:28, Kuogee Hsieh wrote:
> 
> On 2/11/2022 2:40 PM, Dmitry Baryshkov wrote:
>> Currently DP driver will allocate panel bridge for eDP panels. This
>> supports only the following topology:
>>
>> - eDP encoder ⇒ eDP panel (wrapped using panel-bridge)
>>
>> Simplify this code to just check if there is any next bridge in the
>> chain (be it a panel bridge or regular bridge). Rename panel_bridge
>> field to next_bridge accordingly.
>>
>> This allows one to use e.g. one of the following display topologies:
>>
>> - eDP encoder ⇒ ptn3460 ⇒ fixed LVDS panel
>> - eDP encoder ⇒ ptn3460 ⇒ LVDS connector with EDID lines for panel 
>> autodetect
>> - eDP encoder ⇒ ptn3460 ⇒ THC63LVD1024 ⇒ DPI panel.
>> - eDP encoder ⇒ LT8912 ⇒ DSI panel
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> 
>> Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>

The Tested-by got hidden by the quotation symbols. Could you please send 
another one?

> 
>> ---
>>   drivers/gpu/drm/msm/dp/dp_display.c |  2 +-
>>   drivers/gpu/drm/msm/dp/dp_display.h |  2 +-
>>   drivers/gpu/drm/msm/dp/dp_drm.c     |  4 ++--
>>   drivers/gpu/drm/msm/dp/dp_parser.c  | 31 +++++++++++++++--------------
>>   drivers/gpu/drm/msm/dp/dp_parser.h  |  2 +-
>>   5 files changed, 21 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c 
>> b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 44d42c76c2a3..45f9a912ecc5 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -266,7 +266,7 @@ static int dp_display_bind(struct device *dev, 
>> struct device *master,
>>           goto end;
>>       }
>> -    dp->dp_display.panel_bridge = dp->parser->panel_bridge;
>> +    dp->dp_display.next_bridge = dp->parser->next_bridge;
>>       dp->aux->drm_dev = drm;
>>       rc = dp_aux_register(dp->aux);
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h 
>> b/drivers/gpu/drm/msm/dp/dp_display.h
>> index e3adcd578a90..7af2b186d2d9 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
>> @@ -16,7 +16,7 @@ struct msm_dp {
>>       struct drm_bridge *bridge;
>>       struct drm_connector *connector;
>>       struct drm_encoder *encoder;
>> -    struct drm_bridge *panel_bridge;
>> +    struct drm_bridge *next_bridge;
>>       bool is_connected;
>>       bool audio_enabled;
>>       bool power_on;
>> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c 
>> b/drivers/gpu/drm/msm/dp/dp_drm.c
>> index 26ef41a4c1b6..80f59cf99089 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
>> @@ -236,9 +236,9 @@ struct drm_bridge *msm_dp_bridge_init(struct 
>> msm_dp *dp_display, struct drm_devi
>>           return ERR_PTR(rc);
>>       }
>> -    if (dp_display->panel_bridge) {
>> +    if (dp_display->next_bridge) {
>>           rc = drm_bridge_attach(dp_display->encoder,
>> -                    dp_display->panel_bridge, bridge,
>> +                    dp_display->next_bridge, bridge,
>>                       DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>>           if (rc < 0) {
>>               DRM_ERROR("failed to attach panel bridge: %d\n", rc);
>> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c 
>> b/drivers/gpu/drm/msm/dp/dp_parser.c
>> index a7acc23f742b..901d7967370f 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
>> @@ -265,23 +265,16 @@ static int dp_parser_clock(struct dp_parser 
>> *parser)
>>       return 0;
>>   }
>> -static int dp_parser_find_panel(struct dp_parser *parser)
>> +static int dp_parser_find_next_bridge(struct dp_parser *parser)
>>   {
>>       struct device *dev = &parser->pdev->dev;
>> -    struct drm_panel *panel;
>> -    int rc;
>> +    struct drm_bridge *bridge;
>> -    rc = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &panel, NULL);
>> -    if (rc) {
>> -        DRM_ERROR("failed to acquire DRM panel: %d\n", rc);
>> -        return rc;
>> -    }
>> +    bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
>> +    if (IS_ERR(bridge))
>> +        return PTR_ERR(bridge);
>> -    parser->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
>> -    if (IS_ERR(parser->panel_bridge)) {
>> -        DRM_ERROR("failed to create panel bridge\n");
>> -        return PTR_ERR(parser->panel_bridge);
>> -    }
>> +    parser->next_bridge = bridge;
>>       return 0;
>>   }
>> @@ -307,10 +300,18 @@ static int dp_parser_parse(struct dp_parser 
>> *parser, int connector_type)
>>       if (rc)
>>           return rc;
>> +    /*
>> +     * Currently we support external bridges only for eDP connectors.
>> +     *
>> +     * No external bridges are expected for the DisplayPort connector,
>> +     * it is physically present in a form of a DP or USB-C connector.
>> +     */
>>       if (connector_type == DRM_MODE_CONNECTOR_eDP) {
>> -        rc = dp_parser_find_panel(parser);
>> -        if (rc)
>> +        rc = dp_parser_find_next_bridge(parser);
>> +        if (rc) {
>> +            DRM_ERROR("DP: failed to find next bridge\n");
>>               return rc;
>> +        }
>>       }
>>       /* Map the corresponding regulator information according to
>> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h 
>> b/drivers/gpu/drm/msm/dp/dp_parser.h
>> index 3172da089421..4cec851e38d9 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
>> @@ -123,7 +123,7 @@ struct dp_parser {
>>       struct dp_display_data disp_data;
>>       const struct dp_regulator_cfg *regulator_cfg;
>>       u32 max_dp_lanes;
>> -    struct drm_bridge *panel_bridge;
>> +    struct drm_bridge *next_bridge;
>>       int (*parse)(struct dp_parser *parser, int connector_type);
>>   };

-- 
With best wishes
Dmitry