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Message-ID: <0cac7c17-c822-927e-cc15-456b1423689c@linaro.org>
Date:   Sat, 8 Jul 2023 03:32:06 +0300
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Subject: Re: [PATCH v1 5/5] drm/msm/dp: move of_dp_aux_populate_bus() to probe
 for eDP
Content-Language: en-GB
To:     Kuogee Hsieh <quic_khsieh@quicinc.com>,
        dri-devel@lists.freedesktop.org, robdclark@gmail.com,
        sean@poorly.run, swboyd@chromium.org, dianders@chromium.org,
        vkoul@kernel.org, daniel@ffwll.ch, airlied@gmail.com,
        agross@kernel.org, andersson@kernel.org
Cc:     quic_abhinavk@quicinc.com, quic_jesszhan@quicinc.com,
        quic_sbillaka@quicinc.com, marijn.suijten@somainline.org,
        freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <1688773943-3887-1-git-send-email-quic_khsieh@quicinc.com>
 <1688773943-3887-6-git-send-email-quic_khsieh@quicinc.com>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
In-Reply-To: <1688773943-3887-6-git-send-email-quic_khsieh@quicinc.com>
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Precedence: bulk

On 08/07/2023 02:52, Kuogee Hsieh wrote:
> Move of_dp_aux_populate_bus() to dp_display_probe() for eDP
> from dp_display_bind() so that probe deferral cases can be
> handled effectively
> 
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dp/dp_aux.c     | 25 ++++++++++++
>   drivers/gpu/drm/msm/dp/dp_display.c | 79 +++++++++++++++++++------------------
>   2 files changed, 65 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c
> index c592064..c1baffb 100644
> --- a/drivers/gpu/drm/msm/dp/dp_aux.c
> +++ b/drivers/gpu/drm/msm/dp/dp_aux.c
> @@ -505,6 +505,21 @@ void dp_aux_unregister(struct drm_dp_aux *dp_aux)
>   	drm_dp_aux_unregister(dp_aux);
>   }
>   
> +static int dp_wait_hpd_asserted(struct drm_dp_aux *dp_aux,
> +				 unsigned long wait_us)
> +{
> +	int ret;
> +	struct dp_aux_private *aux;
> +
> +	aux = container_of(dp_aux, struct dp_aux_private, dp_aux);
> +
> +	pm_runtime_get_sync(aux->dev);
> +	ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog);
> +	pm_runtime_put_sync(aux->dev);
> +
> +	return ret;
> +}
> +
>   struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog,
>   			      bool is_edp)
>   {
> @@ -528,6 +543,16 @@ struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog,
>   	aux->catalog = catalog;
>   	aux->retry_cnt = 0;
>   
> +	/*
> +	 * Use the drm_dp_aux_init() to use the aux adapter
> +	 * before registering aux with the DRM device.
> +	 */
> +	aux->dp_aux.name = "dpu_dp_aux";
> +	aux->dp_aux.dev = dev;
> +	aux->dp_aux.transfer = dp_aux_transfer;
> +	aux->dp_aux.wait_hpd_asserted = dp_wait_hpd_asserted;
> +	drm_dp_aux_init(&aux->dp_aux);
> +
>   	return &aux->dp_aux;
>   }
>   
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 185f1eb..7ed4bea 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -302,10 +302,6 @@ static int dp_display_bind(struct device *dev, struct device *master,
>   		goto end;
>   	}
>   
> -	pm_runtime_enable(dev);
> -	pm_runtime_set_autosuspend_delay(dev, 1000);
> -	pm_runtime_use_autosuspend(dev);
> -
>   	return 0;
>   end:
>   	return rc;
> @@ -322,8 +318,6 @@ static void dp_display_unbind(struct device *dev, struct device *master,
>   
>   	kthread_stop(dp->ev_tsk);
>   
> -	of_dp_aux_depopulate_bus(dp->aux);
> -
>   	dp_power_client_deinit(dp->power);
>   	dp_unregister_audio_driver(dev, dp->audio);
>   	dp_aux_unregister(dp->aux);
> @@ -1245,6 +1239,29 @@ static const struct msm_dp_desc *dp_display_get_desc(struct platform_device *pde
>   	return NULL;
>   }
>   
> +static void of_dp_aux_depopulate_bus_void(void *data)
> +{
> +	of_dp_aux_depopulate_bus(data);
> +}
> +
> +static int dp_display_auxbus_emulation(struct dp_display_private *dp)

Why is it called emulation?

> +{
> +	struct device *dev = &dp->pdev->dev;
> +	struct device_node *aux_bus;
> +	int ret = 0;
> +
> +	aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> +
> +	if (aux_bus) {
> +		ret = devm_of_dp_aux_populate_bus(dp->aux, NULL);

And here you missed the whole point of why we have been asking for. 
Please add a sensible `done_probing' callback, which will call 
component_add(). This way the DP component will only be registered when 
the panel has been probed. Keeping us from the component binding retries 
and corresponding side effects.

> +
> +		devm_add_action_or_reset(dev, of_dp_aux_depopulate_bus_void,
> +					 dp->aux);

Useless, it's already handled by the devm_ part of the 
devm_of_dp_aux_populate_bus().

> +	}
> +
> +	return ret;
> +}
> +
>   static int dp_display_probe(struct platform_device *pdev)
>   {
>   	int rc = 0;
> @@ -1290,8 +1307,18 @@ static int dp_display_probe(struct platform_device *pdev)
>   
>   	platform_set_drvdata(pdev, &dp->dp_display);
>   
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
> +	pm_runtime_use_autosuspend(&pdev->dev);

Can we have this in probe right from the patch #2?

> +
>   	dp_display_request_irq(dp);
>   
> +	if (dp->dp_display.is_edp) {
> +		rc = dp_display_auxbus_emulation(dp);
> +		if (rc)
> +			DRM_ERROR("eDP aux-bus emulation failed, rc=%d\n", rc);
> +	}
> +
>   	rc = component_add(&pdev->dev, &dp_display_comp_ops);
>   	if (rc) {
>   		DRM_ERROR("component add failed, rc=%d\n", rc);
> @@ -1306,11 +1333,14 @@ static int dp_display_remove(struct platform_device *pdev)
>   	struct dp_display_private *dp = dev_get_dp_display_private(&pdev->dev);
>   
>   	component_del(&pdev->dev, &dp_display_comp_ops);
> -	dp_display_deinit_sub_modules(dp);
> -
>   	platform_set_drvdata(pdev, NULL);
> +
> +	pm_runtime_dont_use_autosuspend(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
>   	pm_runtime_put_sync_suspend(&pdev->dev);
>   
> +	dp_display_deinit_sub_modules(dp);
> +
>   	return 0;
>   }
>   
> @@ -1514,31 +1544,10 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
>   
>   static int dp_display_get_next_bridge(struct msm_dp *dp)
>   {
> -	int rc;
> +	int rc = 0;
>   	struct dp_display_private *dp_priv;
> -	struct device_node *aux_bus;
> -	struct device *dev;
>   
>   	dp_priv = container_of(dp, struct dp_display_private, dp_display);
> -	dev = &dp_priv->pdev->dev;
> -	aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> -
> -	if (aux_bus && dp->is_edp) {
> -		/*
> -		 * The code below assumes that the panel will finish probing
> -		 * by the time devm_of_dp_aux_populate_ep_devices() returns.
> -		 * This isn't a great assumption since it will fail if the
> -		 * panel driver is probed asynchronously but is the best we
> -		 * can do without a bigger driver reorganization.
> -		 */
> -		rc = of_dp_aux_populate_bus(dp_priv->aux, NULL);
> -		of_node_put(aux_bus);
> -		if (rc)
> -			goto error;
> -	} else if (dp->is_edp) {
> -		DRM_ERROR("eDP aux_bus not found\n");
> -		return -ENODEV;
> -	}
>   
>   	/*
>   	 * External bridges are mandatory for eDP interfaces: one has to
> @@ -1551,17 +1560,9 @@ static int dp_display_get_next_bridge(struct msm_dp *dp)
>   	if (!dp->is_edp && rc == -ENODEV)
>   		return 0;
>   
> -	if (!rc) {
> +	if (!rc)
>   		dp->next_bridge = dp_priv->parser->next_bridge;
> -		return 0;
> -	}
>   
> -error:
> -	if (dp->is_edp) {
> -		of_dp_aux_depopulate_bus(dp_priv->aux);
> -		dp_display_host_phy_exit(dp_priv);
> -		dp_display_host_deinit(dp_priv);
> -	}
>   	return rc;
>   }
>   

-- 
With best wishes
Dmitry