# Re: \[PATCH v2 11/29\] iommu/mediatek: Always pm\_runtime\_get while tlb flush

- From: Hsin-Yi Wang \<hidden\>
- Date: 2021-08-24 07:10:42 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2021/08/1486631
- Thread: https://ratatoskr.run/linux-mediatek/2021/08/1476694/t.md

```text
On Fri, Aug 13, 2021 at 2:57 PM Yong Wu [ref] wrote:
>
> Prepare for 2 HWs that sharing pgtable in different power-domains.
>
> The previous SoC don't have PM. Only mt8192 has power-domain,
> and it is display's power-domain which nearly always is enabled.
>
> When there are 2 M4U HWs, it may has problem.
> In this function, we get the pm_status via the m4u dev, but it don't
> reflect the real power-domain status of the HW since there may be other
> HW also use that power-domain.
>
> Currently we could not get the real power-domain status, thus always
> pm_runtime_get here.
>
> Prepare for mt8195, thus, no need fix tags here.
>
> This patch may drop the performance, we expect the user could
> pm_runtime_get_sync before dma_alloc_attrs which need tlb ops.

Can you check if there are existing users that need to add this change?


>
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
<snip>

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