Re: [PATCH v2 11/29] iommu/mediatek: Always pm_runtime_get while tlb flush
From: Hsin-Yi Wang
Date: Tue Aug 24 2021 - 03:10:42 EST
On Fri, Aug 13, 2021 at 2:57 PM Yong Wu <yong.wu@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>