Re: [PATCH 3/5] iommu/sun50i: Ensure bypass is disabled

[Jernej Škrabec]

Dne četrtek, 28. april 2022 ob 03:03:58 CEST je Samuel Holland napisal(a):
> The H6 variant of the hardware disables bypass by default. The D1
> variant of the hardware enables bypass for all masters by default.
> 
> Since the driver expects bypass to be disabled, ensure that is the case.
> 
> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>

Actually, it would be better to set bypass to 0xff and in 
sun50i_iommu_attach_device() clear bypass bit for that particular device. As 
you might notice, index in phandle is currently not used. This would also help 
expose bugs, like missing second iommu channel for Cedrus on H6, but that's 
easy to fix.

Best regards,
Jernej

> ---
> 
>  drivers/iommu/sun50i-iommu.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
> index ec07b60016d3..b9e644b93637 100644
> --- a/drivers/iommu/sun50i-iommu.c
> +++ b/drivers/iommu/sun50i-iommu.c
> @@ -374,6 +374,8 @@ static int sun50i_iommu_enable(struct sun50i_iommu
> *iommu)
> 
>  	spin_lock_irqsave(&iommu->iommu_lock, flags);
> 
> +	iommu_write(iommu, IOMMU_BYPASS_REG, 0);
> +
>  	iommu_write(iommu, IOMMU_TTB_REG, sun50i_domain->dt_dma);
>  	iommu_write(iommu, IOMMU_TLB_PREFETCH_REG,
>  		    IOMMU_TLB_PREFETCH_MASTER_ENABLE(0) |