[PATCH 4/8] etnaviv: iommuv1: remove map_lock

[Wladimir J. van der Laan]

On Fri, Sep 15, 2017 at 07:04:35PM +0200, Lucas Stach wrote:
> It wasn't protecting anything, as the single word writes used to
> set up or tear down a translation are already inherently atomic,
> so the spinlock is pure overhead.
> 
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>

Reviewed-by: Wladimir J. van der Laan <laanwj at gmail.com>

> ---
>  drivers/gpu/drm/etnaviv/etnaviv_iommu.c | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_iommu.c b/drivers/gpu/drm/etnaviv/etnaviv_iommu.c
> index aaa8c4136f53..78a7c0f3064a 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_iommu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_iommu.c
> @@ -42,7 +42,6 @@ struct etnaviv_iommu_domain {
>  	void *bad_page_cpu;
>  	dma_addr_t bad_page_dma;
>  	struct etnaviv_iommu_domain_pgtable pgtable;
> -	spinlock_t map_lock;
>  };
>  
>  static struct etnaviv_iommu_domain *to_etnaviv_domain(struct iommu_domain *domain)
> @@ -90,8 +89,6 @@ static int __etnaviv_iommu_init(struct etnaviv_iommu_domain *etnaviv_domain)
>  		etnaviv_domain->pgtable.pgtable[i] =
>  			etnaviv_domain->bad_page_dma;
>  
> -	spin_lock_init(&etnaviv_domain->map_lock);
> -
>  	return 0;
>  }
>  
> @@ -118,9 +115,7 @@ static int etnaviv_iommuv1_map(struct iommu_domain *domain, unsigned long iova,
>  	if (size != SZ_4K)
>  		return -EINVAL;
>  
> -	spin_lock(&etnaviv_domain->map_lock);
>  	pgtable_write(&etnaviv_domain->pgtable, iova, paddr);
> -	spin_unlock(&etnaviv_domain->map_lock);
>  
>  	return 0;
>  }
> @@ -133,10 +128,8 @@ static size_t etnaviv_iommuv1_unmap(struct iommu_domain *domain,
>  	if (size != SZ_4K)
>  		return -EINVAL;
>  
> -	spin_lock(&etnaviv_domain->map_lock);
>  	pgtable_write(&etnaviv_domain->pgtable, iova,
>  		      etnaviv_domain->bad_page_dma);
> -	spin_unlock(&etnaviv_domain->map_lock);
>  
>  	return SZ_4K;
>  }
> -- 
> 2.11.0
> 
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