linux-kernel - Re: [PATCH v2 1/7] iommu/exynos: Reuse SysMMU constants for page size and order

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Date:   Tue, 12 Jul 2022 17:39:06 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Sam Protsenko <semen.protsenko@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Janghyuck Kim <janghyuck.kim@...sung.com>,
        Cho KyongHo <pullip.cho@...sung.com>,
        Daniel Mentz <danielmentz@...gle.com>,
        David Virag <virag.david003@...il.com>,
        Sumit Semwal <sumit.semwal@...aro.org>, iommu@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/7] iommu/exynos: Reuse SysMMU constants for page
 size and order


On 11.07.2022 01:05, Sam Protsenko wrote:
> Using SZ_4K in context of SysMMU driver is better than using PAGE_SIZE,
> as PAGE_SIZE might have different value on different platforms. Though
> it would be even better to use more specific constants, already existing
> in SysMMU driver. Make the code more strict by using SPAGE_ORDER and
> SPAGE_SIZE constants.
>
> It also makes sense, as __sysmmu_tlb_invalidate_entry() also uses
> SPAGE_* constants for further calculations with num_inv param, so it's
> logical that num_inv should be previously calculated using also SPAGE_*
> values.
>
> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>

Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>

> ---
> Changes in v2:
>    - (none) This patch is new and added in v2
>
>   drivers/iommu/exynos-iommu.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 79729892eb48..8f80aaa35092 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -340,7 +340,7 @@ static void __sysmmu_set_ptbase(struct sysmmu_drvdata *data, phys_addr_t pgd)
>   	if (MMU_MAJ_VER(data->version) < 5)
>   		writel(pgd, data->sfrbase + REG_PT_BASE_ADDR);
>   	else
> -		writel(pgd / SZ_4K, data->sfrbase + REG_V5_PT_BASE_PFN);
> +		writel(pgd >> SPAGE_ORDER, data->sfrbase + REG_V5_PT_BASE_PFN);
>   
>   	__sysmmu_tlb_invalidate(data);
>   }
> @@ -550,7 +550,7 @@ static void sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
>   		 * 64KB page can be one of 16 consecutive sets.
>   		 */
>   		if (MMU_MAJ_VER(data->version) == 2)
> -			num_inv = min_t(unsigned int, size / SZ_4K, 64);
> +			num_inv = min_t(unsigned int, size / SPAGE_SIZE, 64);
>   
>   		if (sysmmu_block(data)) {
>   			__sysmmu_tlb_invalidate_entry(data, iova, num_inv);

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland