Re: [PATCH v3 2/3] drm/msm/dpu: handle failures while initializing displays

[Jordan Crouse <jcrouse-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

On Thu, Dec 13, 2018 at 10:51:03AM -0800, Jeykumar Sankaran wrote:
> Bail out KMS hw init on display initialization failures with
> proper error logging.
> 
> changes in v3:
> 	- introduced in the series
> 
> Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 39 +++++++++++++++++++++++----------
>  1 file changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 685686e..39c8549 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -405,33 +405,36 @@ static void dpu_kms_wait_for_commit_done(struct msm_kms *kms,
>  	}
>  }
>  
> -static void _dpu_kms_initialize_dsi(struct drm_device *dev,
> +static int _dpu_kms_initialize_dsi(struct drm_device *dev,
>  				    struct msm_drm_private *priv,
>  				    struct dpu_kms *dpu_kms)
>  {
>  	struct drm_encoder *encoder = NULL;
> -	int i, rc;
> +	int i, rc = 0;
> +
> +	if (!(priv->dsi[0] || priv->dsi[1]))
> +		return rc;
>  
>  	/*TODO: Support two independent DSI connectors */
>  	encoder = dpu_encoder_init(dev, DRM_MODE_ENCODER_DSI);
> -	if (IS_ERR_OR_NULL(encoder)) {
> +	if (IS_ERR(encoder)) {
>  		DPU_ERROR("encoder init failed for dsi display\n");
> -		return;
> +		return PTR_ERR(encoder);
>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(priv->dsi); i++) {
> -		if (!priv->dsi[i]) {
> -			DPU_DEBUG("invalid msm_dsi for ctrl %d\n", i);
> -			return;
> -		}
> +		if (!priv->dsi[i])
> +			continue;
>  
>  		rc = msm_dsi_modeset_init(priv->dsi[i], dev, encoder);
>  		if (rc) {
>  			DPU_ERROR("modeset_init failed for dsi[%d], rc = %d\n",
>  				i, rc);
> -			continue;
> +			return rc;
>  		}
>  	}
> +
> +	return rc;

This also looks like one of those cases where you can drop out of the if
statement to return rc.
>  }
>  
>  /**
> @@ -442,16 +445,24 @@ static void _dpu_kms_initialize_dsi(struct drm_device *dev,
>   * @dpu_kms:    Pointer to dpu kms structure
>   * Returns:     Zero on success
>   */
> -static void _dpu_kms_setup_displays(struct drm_device *dev,
> +static int _dpu_kms_setup_displays(struct drm_device *dev,
>  				    struct msm_drm_private *priv,
>  				    struct dpu_kms *dpu_kms)
>  {
> -	_dpu_kms_initialize_dsi(dev, priv, dpu_kms);
> +	int rc = 0;
> +
> +	rc = _dpu_kms_initialize_dsi(dev, priv, dpu_kms);
> +	if (rc) {
> +		DPU_ERROR("failed to initialize dsi, rc = %d\n", rc);
> +		return rc;
> +	}
>  
>  	/**
>  	 * Extend this function to initialize other
>  	 * types of displays
>  	 */
> +
> +	return rc;

Here too.

>  }
>  
>  static void _dpu_kms_drm_obj_destroy(struct dpu_kms *dpu_kms)
> @@ -517,7 +528,11 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
>  	 * Create encoder and query display drivers to create
>  	 * bridges and connectors
>  	 */
> -	_dpu_kms_setup_displays(dev, priv, dpu_kms);
> +	ret = _dpu_kms_setup_displays(dev, priv, dpu_kms);
> +	if (ret) {
> +		DPU_ERROR("failed to setup display, rc = %d\n", ret);

You don't need to pile on with another error message.

> +		goto fail;
> +	}
>  
>  	max_crtc_count = min(catalog->mixer_count,
>  			     (u32)dev->mode_config.num_encoder);

-- 
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a Linux Foundation Collaborative Project
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