Re: [PATCH 4/4] iommu/msm: Mark driver BROKEN

[Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

Adding Mitch H. and Rob Clark.

On 2/3/2015 11:58 PM, Thierry Reding wrote:
> From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>
> The MSM IOMMU driver unconditionally calls bus_set_iommu(), which is a
> very stupid thing to do on multi-platform kernels. While marking the
> driver BROKEN may seem a little extreme, there is no other way to make
> the driver skip initialization. One of the problems is that it doesn't
> have devicetree binding documentation and the driver doesn't contain a
> struct of_device_id table either, so no way to check that it is indeed
> valid to set up the IOMMU operations for this driver.
>
> This fixes a problem on Tegra20 where the DRM driver will try to use the
> obviously non-existent MSM IOMMU.
>
> Marking the driver BROKEN shouldn't do any harm, since there aren't any
> users currently. There is no struct of_device_id table, so the device
> can't be instantiated from device tree, and I couldn't find any code
> that would instantiate a matching platform_device either, so the driver
> is effectively unused.
>
> Reported-by: Nicolas Chauvet <kwizart-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Cc: David Brown <davidb-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Cc: Daniel Walker <dwalker-zu3NM2574RrQT0dZR+AlfA@public.gmane.org>
> Cc: Bryan Huntsman <bryanh-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Cc: Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
>   drivers/iommu/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 325188eef1c1..0f70bc1fce65 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -31,6 +31,7 @@ config FSL_PAMU
>   config MSM_IOMMU
>   	bool "MSM IOMMU Support"
>   	depends on ARCH_MSM8X60 || ARCH_MSM8960
> +	depends on BROKEN
>   	select IOMMU_API
>   	help
>   	  Support for the IOMMUs found on certain Qualcomm SOCs.
>


.Olav

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