Re: [PATCH 3/4] drm/i915: Handle error return from dma_set_coherent_mask()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 12, 2016 at 04:18:51PM +0300, Imre Deak wrote:
> A failure from these functions can lead to obscure bugs later, so it's
> better not to suppress them and just fail module loading.

Based on a cursory examination looks like this should never fail, but I
suppose having the error handling won't hurt, so

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 0eadeb6..a7fa82e 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1262,8 +1262,15 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
>  	pci_set_master(dev->pdev);
>  
>  	/* overlay on gen2 is broken and can't address above 1G */
> -	if (IS_GEN2(dev))
> -		dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(30));
> +	if (IS_GEN2(dev)) {
> +		ret = dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(30));
> +		if (ret) {
> +			DRM_ERROR("failed to set DMA mask\n");
> +
> +			goto out_ggtt;
> +		}
> +	}
> +
>  
>  	/* 965GM sometimes incorrectly writes to hardware status page (HWS)
>  	 * using 32bit addressing, overwriting memory if HWS is located
> @@ -1273,8 +1280,15 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
>  	 * behaviour if any general state is accessed within a page above 4GB,
>  	 * which also needs to be handled carefully.
>  	 */
> -	if (IS_BROADWATER(dev) || IS_CRESTLINE(dev))
> -		dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(32));
> +	if (IS_BROADWATER(dev) || IS_CRESTLINE(dev)) {
> +		ret = dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(32));
> +
> +		if (ret) {
> +			DRM_ERROR("failed to set DMA mask\n");
> +
> +			goto out_ggtt;
> +		}
> +	}
>  
>  	aperture_size = ggtt->mappable_end;
>  
> -- 
> 2.5.0
> 
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-- 
Ville Syrjälä
Intel OTC
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