Re: [PATCH v3 09/33] iommu/mediatek: Remove for_each_m4u in tlb_sync_all

[AngeloGioacchino Del Regno]

Il 23/09/21 13:58, Yong Wu ha scritto:
> The tlb_sync_all is called from these three functions:
> a) flush_iotlb_all: it will be called for each a iommu HW.
> b) tlb_flush_range_sync: it already has for_each_m4u.
> c) in irq: When IOMMU HW translation fault, Only need flush itself.
>
> Thus, No need for_each_m4u in this tlb_sync_all. Remove it.
>
> Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> ---
>   drivers/iommu/mtk_iommu.c | 18 +++++++-----------
>   1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 6f4f6624e3ac..0b4c30baa864 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -206,19 +206,15 @@ static struct mtk_iommu_domain *to_mtk_domain(struct iommu_domain *dom)
>   
>   static void mtk_iommu_tlb_flush_all(struct mtk_iommu_data *data)
>   {
> -	struct list_head *head = data->hw_list;
> -
> -	for_each_m4u(data, head) {
> -		if (pm_runtime_get_if_in_use(data->dev) <= 0)
> -			continue;
> +	if (pm_runtime_get_if_in_use(data->dev) <= 0)
> +		return;
>   
> -		writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
> -			       data->base + data->plat_data->inv_sel_reg);
> -		writel_relaxed(F_ALL_INVLD, data->base + REG_MMU_INVALIDATE);
> -		wmb(); /* Make sure the tlb flush all done */
> +	writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
> +		       data->base + data->plat_data->inv_sel_reg);
> +	writel_relaxed(F_ALL_INVLD, data->base + REG_MMU_INVALIDATE);
> +	wmb(); /* Make sure the tlb flush all done */

There aren't a lot of writes here - not anymore, since you are no longer doing
this for_each_m4u()...
...so, please change writel_relaxed() to writel() calls, allowing you to also
remove the write barrier at the end (since in the non relaxed version, order
is already ensured).

>   
> -		pm_runtime_put(data->dev);
> -	}
> +	pm_runtime_put(data->dev);
>   }
>   
>   static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,