Re: [PATCH 2/4] iommu/omap: Play nice in multi-platform builds

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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On Wed, Feb 04, 2015 at 11:37:52AM -0600, Suman Anna wrote:
> Hi Thierry,
> 
> On 02/04/2015 08:31 AM, Laurent Pinchart wrote:
> > Hi Thierry,
> > 
> > Thank you for the patch.
> > 
> > On Wednesday 04 February 2015 08:58:08 Thierry Reding wrote:
> >> From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> >>
> >> The OMAP IOMMU driver unconditionally executes code and registers a
> >> struct iommu_ops with the platform bus irrespective of whether it runs
> >> on an OMAP SoC or not. This causes problems in multi-platform kernels
> >> where drivers for other SoCs will no longer be able to register their
> >> own struct iommu_ops or even try to use a struct iommu_ops for an IOMMU
> >> that obviously isn't there.
> >>
> >> The smallest fix I could think of is to check for the existence of any
> >> OMAP IOMMU devices in the device tree and skip initialization otherwise.
> >>
> >> This fixes a problem on Tegra20 where the DRM driver will try to use the
> >> obviously non-existent OMAP IOMMU.
> >>
> >> Reported-by: Nicolas Chauvet <kwizart-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >> Cc: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
> >> Cc: Suman Anna <s-anna-l0cyMroinI0@public.gmane.org>
> >> Cc: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
> >> Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> >> ---
> >>  drivers/iommu/omap-iommu.c | 6 ++++++
> >>  1 file changed, 6 insertions(+)
> >>
> >> diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
> >> index bbb7dcef02d3..e4d4f133a3b3 100644
> >> --- a/drivers/iommu/omap-iommu.c
> >> +++ b/drivers/iommu/omap-iommu.c
> >> @@ -1377,6 +1377,9 @@ static int __init omap_iommu_init(void)
> >>  	const unsigned long flags = SLAB_HWCACHE_ALIGN;
> >>  	size_t align = 1 << 10; /* L2 pagetable alignement */
> >>
> >> +	if (!of_find_matching_node(NULL, omap_iommu_of_match))
> >> +		return 0;
> >> +
> 
> Need to call the of_node_put on the cases it succeeds right, you should
> change this to the semantics you used in the arm-smmu driver.

Good point. I've sent out an updated set of patches.

Thierry

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