linux-kernel - Re: [PATCH 4/4] drm/vmwgfx: unwind spaghetti code in vmw_dma_select

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Date:   Tue, 8 Jan 2019 10:56:47 +0000
From:   Thomas Hellstrom <thellstrom@...are.com>
To:     "hch@....de" <hch@....de>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Linux-graphics-maintainer <Linux-graphics-maintainer@...are.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
Subject: Re: [PATCH 4/4] drm/vmwgfx: unwind spaghetti code in
 vmw_dma_select_mode

On Sat, 2019-01-05 at 09:01 +0100, Christoph Hellwig wrote:
> Just use a simple if/else chain to select the DMA mode.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>

Reviewed-by: Thomas Hellstrom <thellstrom@...are.com>


> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 25 ++++++-------------------
>  1 file changed, 6 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> index c2060f6cc9e8..86387735a90b 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> @@ -566,34 +566,21 @@ static int vmw_dma_select_mode(struct
> vmw_private *dev_priv)
>  		[vmw_dma_map_populate] = "Keeping DMA mappings.",
>  		[vmw_dma_map_bind] = "Giving up DMA mappings early."};
>  
> -	if (intel_iommu_enabled) {
> +	if (vmw_force_coherent)
> +		dev_priv->map_mode = vmw_dma_alloc_coherent;
> +	else if (intel_iommu_enabled)
>  		dev_priv->map_mode = vmw_dma_map_populate;
> -		goto out_fixup;
> -	}
> -
> -	if (!(vmw_force_iommu || vmw_force_coherent)) {
> +	else if (!vmw_force_iommu)
>  		dev_priv->map_mode = vmw_dma_phys;
> -		DRM_INFO("DMA map mode: %s\n", names[dev_priv-
> >map_mode]);
> -		return 0;
> -	}
> -
> -#ifdef CONFIG_SWIOTLB
> -	if (swiotlb_nr_tbl())
> +	else if (IS_ENABLED(CONFIG_SWIOTLB) && swiotlb_nr_tbl())
>  		dev_priv->map_mode = vmw_dma_alloc_coherent;
>  	else
> -#endif
>  		dev_priv->map_mode = vmw_dma_map_populate;
>  
> -out_fixup:
> -	if (dev_priv->map_mode == vmw_dma_map_populate &&
> -	    vmw_restrict_iommu)
> +	if (dev_priv->map_mode == vmw_dma_map_populate &&
> vmw_restrict_iommu)
>  		dev_priv->map_mode = vmw_dma_map_bind;
>  
> -	if (vmw_force_coherent)
> -		dev_priv->map_mode = vmw_dma_alloc_coherent;
> -
>  	DRM_INFO("DMA map mode: %s\n", names[dev_priv->map_mode]);
> -
>  	return 0;
>  }
>