On Wed, 2021-12-08 at 14:07 +0200, Dafna Hirschfeld wrote:
> From: Sebastian Reichel <[email protected]>
> 
> In case of v4l2_reqbufs() it is possible, that a TLB flush is done
> without runtime PM being enabled. In that case the "Partial TLB flush
> timed out, falling back to full flush" warning is printed.
> 
> Commit c0b57581b73b ("iommu/mediatek: Add power-domain operation")
> introduced has_pm as optimization to avoid checking runtime PM
> when there is no power domain attached. But without the PM domain
> there is still the device driver's runtime PM suspend handler, which
> disables the clock. Thus flushing should also be avoided when there
> is no PM domain involved.
> 
> Signed-off-by: Sebastian Reichel <[email protected]>
> Reviewed-by: Dafna Hirschfeld <[email protected]>

Reviewed-by: Yong Wu <[email protected]>

> ---
>  drivers/iommu/mtk_iommu.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 342aa562ab6a..dd2c08c54df4 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -225,16 +225,13 @@ static void
> mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
>                                          size_t granule,
>                                          struct mtk_iommu_data *data)
>  {
> -     bool has_pm = !!data->dev->pm_domain;
>       unsigned long flags;
>       int ret;
>       u32 tmp;
>  
>       for_each_m4u(data) {
> -             if (has_pm) {
> -                     if (pm_runtime_get_if_in_use(data->dev) <= 0)
> -                             continue;
> -             }
> +             if (pm_runtime_get_if_in_use(data->dev) <= 0)
> +                     continue;
>  
>               spin_lock_irqsave(&data->tlb_lock, flags);
>               writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
> @@ -259,8 +256,7 @@ static void
> mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
>               writel_relaxed(0, data->base + REG_MMU_CPE_DONE);
>               spin_unlock_irqrestore(&data->tlb_lock, flags);
>  
> -             if (has_pm)
> -                     pm_runtime_put(data->dev);
> +             pm_runtime_put(data->dev);
>       }
>  }
>  
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