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 <[email protected]>
>>
>> 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 <[email protected]>
>> Cc: Tony Lindgren <[email protected]>
>> Cc: Suman Anna <[email protected]>
>> Cc: Laurent Pinchart <[email protected]>
>> Signed-off-by: Thierry Reding <[email protected]>
>> ---
>> 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.
>
> We should convert the omap-iommu driver to proper DT instantiation, but this
> should do for now.
Agreed, and I think this check is better than the iommu_present check
used in some of the other IOMMU drivers, as that would work for a SoC
family only if that is the first one getting registered.
regards
Suman
>
>> p = kmem_cache_create("iopte_cache", IOPTE_TABLE_SIZE, align, flags,
>> iopte_cachep_ctor);
>> if (!p)
>> @@ -1394,6 +1397,9 @@ subsys_initcall(omap_iommu_init);
>>
>> static void __exit omap_iommu_exit(void)
>> {
>> + if (!of_find_matching_node(NULL, omap_iommu_of_match))
>> + return;
>> +
>> kmem_cache_destroy(iopte_cachep);
>>
>> platform_driver_unregister(&omap_iommu_driver);
>
> The exit function will never be called as the omap-iommu driver is always
> built-in. You could just remove the exit function.
>
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