Re: [PATCH 2/4] media: omap3isp: Handle ARM dma_iommu_mapping

[Sicelo <absicsz@gmail.com>]

Hi

On Mon, Oct 28, 2024 at 05:58:36PM +0000, Robin Murphy wrote:
> It's no longer practical for the OMAP IOMMU driver to trick
> arm_setup_iommu_dma_ops() into ignoring its presence, so let's use the
> same tactic as other IOMMU API users on 32-bit ARM and explicitly kick
> the arch code's dma_iommu_mapping out of the way to avoid problems.
> 
> Fixes: 4720287c7bf7 ("iommu: Remove struct iommu_ops *iommu from arch_setup_dma_ops()")
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/media/platform/ti/omap3isp/isp.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/media/platform/ti/omap3isp/isp.c b/drivers/media/platform/ti/omap3isp/isp.c
> index 91101ba88ef0..b2210841a320 100644
> --- a/drivers/media/platform/ti/omap3isp/isp.c
> +++ b/drivers/media/platform/ti/omap3isp/isp.c
> @@ -1961,6 +1961,13 @@ static int isp_attach_iommu(struct isp_device *isp)
>  	struct dma_iommu_mapping *mapping;
>  	int ret;
>  
> +	/* We always want to replace any default mapping from the arch code */
> +	mapping = to_dma_iommu_mapping(isp->dev);
> +	if (mapping) {
> +		arm_iommu_detach_device(isp->dev);
> +		arm_iommu_release_mapping(mapping);
> +	}
> +
>  	/*
>  	 * Create the ARM mapping, used by the ARM DMA mapping core to allocate
>  	 * VAs. This will allocate a corresponding IOMMU domain.
> -- 
> 2.39.2.101.g768bb238c484.dirty
> 

I have finally found time to test this patch on the Nokia N900 and can
confirm it is working fine.

I was wondering - is there a reason that it is not merged yet? I tested
on 6.14-rc2, which did not have it, and notice it is also not in
linux-next.

If it helps:

Tested-by: Sicelo A. Mhlongo <absicsz@gmail.com>