Re: [PATCHv3 7/7] drm/msm/a6xx: Add support for using system cache(LLC)

[Will Deacon]

On Mon, Jun 29, 2020 at 09:22:50PM +0530, Sai Prakash Ranjan wrote:
> diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
> index f455c597f76d..bd1d58229cc2 100644
> --- a/drivers/gpu/drm/msm/msm_iommu.c
> +++ b/drivers/gpu/drm/msm/msm_iommu.c
> @@ -218,6 +218,9 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
>  		iova |= GENMASK_ULL(63, 49);
>  
>  
> +	if (mmu->features & MMU_FEATURE_USE_SYSTEM_CACHE)
> +		prot |= IOMMU_SYS_CACHE_ONLY;

Given that I think this is the only user of IOMMU_SYS_CACHE_ONLY, then it
looks like it should actually be a property on the domain because we never
need to configure it on a per-mapping basis within a domain, and therefore
it shouldn't be exposed by the IOMMU API as a prot flag.

Do you agree?

Will