[v3,6/7] iommu/mediatek: Use writel for TLB range invalidation
diff mbox series

Message ID 1571035101-4213-7-git-send-email-yong.wu@mediatek.com
State New
Headers show
Series
  • Improve tlb range flush
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Commit Message

Yong Wu Oct. 14, 2019, 6:38 a.m. UTC
Use writel for the register F_MMU_INV_RANGE which is for triggering the
HW work. We expect all the setting(iova_start/iova_end...) have already
been finished before F_MMU_INV_RANGE.

Signed-off-by: Anan.Sun <anan.sun@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/iommu/mtk_iommu.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Robin Murphy Oct. 14, 2019, 2:04 p.m. UTC | #1
On 14/10/2019 07:38, Yong Wu wrote:
> Use writel for the register F_MMU_INV_RANGE which is for triggering the
> HW work. We expect all the setting(iova_start/iova_end...) have already
> been finished before F_MMU_INV_RANGE.

For Arm CPUs, these registers should be mapped as Device memory, 
therefore the same-peripheral rule should implicitly enforce that the 
accesses are made in program order, hence you're unlikely to have seen a 
problem in reality. However, the logical reasoning for the change seems 
valid in general, so I'd argue that it's still worth making if only for 
the sake of good practice:

Acked-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Anan.Sun <anan.sun@mediatek.com>
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>   drivers/iommu/mtk_iommu.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index dbbacc3..d285457 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -187,8 +187,7 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
>   		writel_relaxed(iova, data->base + REG_MMU_INVLD_START_A);
>   		writel_relaxed(iova + size - 1,
>   			       data->base + REG_MMU_INVLD_END_A);
> -		writel_relaxed(F_MMU_INV_RANGE,
> -			       data->base + REG_MMU_INVALIDATE);
> +		writel(F_MMU_INV_RANGE, data->base + REG_MMU_INVALIDATE);
>   
>   		/* tlb sync */
>   		ret = readl_poll_timeout_atomic(data->base + REG_MMU_CPE_DONE,
>
Yong Wu Oct. 15, 2019, 5:25 a.m. UTC | #2
On Mon, 2019-10-14 at 15:04 +0100, Robin Murphy wrote:
> On 14/10/2019 07:38, Yong Wu wrote:
> > Use writel for the register F_MMU_INV_RANGE which is for triggering the
> > HW work. We expect all the setting(iova_start/iova_end...) have already
> > been finished before F_MMU_INV_RANGE.
> 
> For Arm CPUs, these registers should be mapped as Device memory, 
> therefore the same-peripheral rule should implicitly enforce that the 
> accesses are made in program order, hence you're unlikely to have seen a 
> problem in reality. However, the logical reasoning for the change seems 
> valid in general, so I'd argue that it's still worth making if only for 
> the sake of good practice:
> 
> Acked-by: Robin Murphy <robin.murphy@arm.com>

Thanks very much for the view. If this patch is not so necessary, I will
remove it this time.

> 
> > Signed-off-by: Anan.Sun <anan.sun@mediatek.com>
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> >   drivers/iommu/mtk_iommu.c | 3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index dbbacc3..d285457 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -187,8 +187,7 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
> >   		writel_relaxed(iova, data->base + REG_MMU_INVLD_START_A);
> >   		writel_relaxed(iova + size - 1,
> >   			       data->base + REG_MMU_INVLD_END_A);
> > -		writel_relaxed(F_MMU_INV_RANGE,
> > -			       data->base + REG_MMU_INVALIDATE);
> > +		writel(F_MMU_INV_RANGE, data->base + REG_MMU_INVALIDATE);
> >   
> >   		/* tlb sync */
> >   		ret = readl_poll_timeout_atomic(data->base + REG_MMU_CPE_DONE,
> > 
> 
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

Patch
diff mbox series

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index dbbacc3..d285457 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -187,8 +187,7 @@  static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 		writel_relaxed(iova, data->base + REG_MMU_INVLD_START_A);
 		writel_relaxed(iova + size - 1,
 			       data->base + REG_MMU_INVLD_END_A);
-		writel_relaxed(F_MMU_INV_RANGE,
-			       data->base + REG_MMU_INVALIDATE);
+		writel(F_MMU_INV_RANGE, data->base + REG_MMU_INVALIDATE);
 
 		/* tlb sync */
 		ret = readl_poll_timeout_atomic(data->base + REG_MMU_CPE_DONE,