Re: [PATCH] drm/msm: Initialize MDSS irq domain at probe time

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 25/11/2021 18:09, AngeloGioacchino Del Regno wrote:
> Since commit 8f59ee9a570c ("drm/msm/dsi: Adjust probe order"), the
> DSI host gets initialized earlier, but this caused unability to probe
> the entire stack of components because they all depend on interrupts
> coming from the main `mdss` node (mdp5, or dpu1).
> 
> To fix this issue, also anticipate probing mdp5 or dpu1 by initializing
> them at msm_pdev_probe() time: this will make sure that we add the
> required interrupt controller mapping before dsi and/or other components
> try to initialize, finally satisfying the dependency.
> 
> While at it, also change the allocation of msm_drm_private to use the
> devm variant of kzalloc().
> 
> Fixes: 8f59ee9a570c ("drm/msm/dsi: Adjust probe order")
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Another issue (or a pack of issues):
Now the msm_drm_init() is unbalanced with msm_drm_uninit(). Bits of code 
(putting the drm dev, removing the IRQ domain, etc) have to be called 
now from the msm_pdev_remove() function rather than from the unbind path.

The following changes fix the observed issues here, however additional 
care should be taken.

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 5a92417d21d0..0abb16256b61 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -342,7 +342,6 @@ static int msm_drm_uninit(struct device *dev)
         struct drm_device *ddev = platform_get_drvdata(pdev);
         struct msm_drm_private *priv = ddev->dev_private;
         struct msm_kms *kms = priv->kms;
-       struct msm_mdss *mdss = priv->mdss;
         int i;

         /*
@@ -402,14 +401,7 @@ static int msm_drm_uninit(struct device *dev)

         component_unbind_all(dev, ddev);

-       if (mdss && mdss->funcs)
-               mdss->funcs->destroy(ddev);
-
-       ddev->dev_private = NULL;
-       drm_dev_put(ddev);
-
         destroy_workqueue(priv->wq);
-       kfree(priv);

         return 0;
  }
@@ -515,7 +507,6 @@ static int msm_drm_init(struct device *dev, const
         struct drm_device *ddev = platform_get_drvdata(pdev);
         struct msm_drm_private *priv = ddev->dev_private;
         struct msm_kms *kms = priv->kms;
-       struct msm_mdss *mdss = priv->mdss;
         int ret, i;

         priv->wq = alloc_ordered_workqueue("msm", 0);
@@ -538,12 +529,12 @@ static int msm_drm_init(struct device *dev, const

         ret = msm_init_vram(ddev);
         if (ret)
-               goto err_destroy_mdss;
+               return ret;

         /* Bind all our sub-components: */
         ret = component_bind_all(dev, ddev);
         if (ret)
-               goto err_destroy_mdss;
+               return ret;

         dma_set_max_seg_size(dev, UINT_MAX);

@@ -649,10 +640,6 @@ static int msm_drm_init(struct device *dev, const
  err_msm_uninit:
         msm_drm_uninit(dev);
         return ret;
-err_destroy_mdss:
-       if (mdss && mdss->funcs)
-               mdss->funcs->destroy(ddev);
-       return ret;
  }

  /*
@@ -1424,9 +1411,20 @@ static int msm_pdev_probe(struct platform_device

  static int msm_pdev_remove(struct platform_device *pdev)
  {
+       struct drm_device *ddev = platform_get_drvdata(pdev);
+       struct msm_drm_private *priv = ddev->dev_private;
+       struct msm_mdss *mdss = priv->mdss;
+
         component_master_del(&pdev->dev, &msm_drm_ops);
+
         of_platform_depopulate(&pdev->dev);

+       if (mdss && mdss->funcs)
+               mdss->funcs->destroy(ddev);
+
+       ddev->dev_private = NULL;
+       drm_dev_put(ddev);
+
         return 0;
  }



> ---
>   drivers/gpu/drm/msm/msm_drv.c | 81 ++++++++++++++++-------------------
>   1 file changed, 38 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 7936e8d498dd..790acf4993c0 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -512,45 +512,12 @@ static int msm_init_vram(struct drm_device *dev)
>   static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   {
>   	struct platform_device *pdev = to_platform_device(dev);
> -	struct drm_device *ddev;
> -	struct msm_drm_private *priv;
> -	struct msm_kms *kms;
> -	struct msm_mdss *mdss;
> +	struct drm_device *ddev = platform_get_drvdata(pdev);
> +	struct msm_drm_private *priv = ddev->dev_private;
> +	struct msm_kms *kms = priv->kms;
> +	struct msm_mdss *mdss = priv->mdss;
>   	int ret, i;
>   
> -	ddev = drm_dev_alloc(drv, dev);
> -	if (IS_ERR(ddev)) {
> -		DRM_DEV_ERROR(dev, "failed to allocate drm_device\n");
> -		return PTR_ERR(ddev);
> -	}
> -
> -	platform_set_drvdata(pdev, ddev);
> -
> -	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> -	if (!priv) {
> -		ret = -ENOMEM;
> -		goto err_put_drm_dev;
> -	}
> -
> -	ddev->dev_private = priv;
> -	priv->dev = ddev;
> -
> -	switch (get_mdp_ver(pdev)) {
> -	case KMS_MDP5:
> -		ret = mdp5_mdss_init(ddev);
> -		break;
> -	case KMS_DPU:
> -		ret = dpu_mdss_init(ddev);
> -		break;
> -	default:
> -		ret = 0;
> -		break;
> -	}
> -	if (ret)
> -		goto err_free_priv;
> -
> -	mdss = priv->mdss;
> -
>   	priv->wq = alloc_ordered_workqueue("msm", 0);
>   	priv->hangcheck_period = DRM_MSM_HANGCHECK_DEFAULT_PERIOD;
>   
> @@ -685,11 +652,6 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   err_destroy_mdss:
>   	if (mdss && mdss->funcs)
>   		mdss->funcs->destroy(ddev);
> -err_free_priv:
> -	kfree(priv);
> -err_put_drm_dev:
> -	drm_dev_put(ddev);
> -	platform_set_drvdata(pdev, NULL);
>   	return ret;
>   }
>   
> @@ -1382,12 +1344,42 @@ static const struct component_master_ops msm_drm_ops = {
>   static int msm_pdev_probe(struct platform_device *pdev)
>   {
>   	struct component_match *match = NULL;
> +	struct msm_drm_private *priv;
> +	struct drm_device *ddev;
>   	int ret;
>   
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	ddev = drm_dev_alloc(&msm_driver, &pdev->dev);
> +	if (IS_ERR(ddev)) {
> +		DRM_DEV_ERROR(&pdev->dev, "failed to allocate drm_device\n");
> +		return PTR_ERR(ddev);
> +	}
> +
> +	platform_set_drvdata(pdev, ddev);
> +	ddev->dev_private = priv;
> +	priv->dev = ddev;
> +
> +	switch (get_mdp_ver(pdev)) {
> +	case KMS_MDP5:
> +		ret = mdp5_mdss_init(ddev);
> +		break;
> +	case KMS_DPU:
> +		ret = dpu_mdss_init(ddev);
> +		break;
> +	default:
> +		ret = 0;
> +		break;
> +	}
> +	if (ret)
> +		goto err_put_drm_dev;
> +
>   	if (get_mdp_ver(pdev)) {
>   		ret = add_display_components(pdev, &match);
>   		if (ret)
> -			return ret;
> +			goto fail;
>   	}
>   
>   	ret = add_gpu_components(&pdev->dev, &match);
> @@ -1409,6 +1401,9 @@ static int msm_pdev_probe(struct platform_device *pdev)
>   
>   fail:
>   	of_platform_depopulate(&pdev->dev);
> +err_put_drm_dev:
> +	drm_dev_put(ddev);
> +	platform_set_drvdata(pdev, NULL);
>   	return ret;
>   }
>   
> 


-- 
With best wishes
Dmitry