[PATCH 2/2] drm/tegra: Acquire a reference to the IOVA cache

[Dmitry Osipenko]

On 23.04.2018 11:34, Dmitry Osipenko wrote:
> On 23.04.2018 09:57, Thierry Reding wrote:
>> From: Thierry Reding <treding at nvidia.com>
>>
>> The IOVA API uses a memory cache to allocate IOVA nodes from. To make
>> sure that this cache is available, obtain a reference to it and release
>> the reference when the cache is no longer needed.
>>
>> On 64-bit ARM this is hidden by the fact that the DMA mapping API gets
>> that reference and never releases it. On 32-bit ARM, however, the DMA
>> mapping API doesn't do that, so allocation of IOVA nodes fails.
>>
>> Signed-off-by: Thierry Reding <treding at nvidia.com>
>> ---
> 
> Reviewed-by: Dmitry Osipenko <digetx at gmail.com>
> Tested-by: Dmitry Osipenko <digetx at gmail.com>
> 
> CONFIG_TEGRA_IOMMU_SMMU is enabled in the default kernel configs and hence DRM
> should fail to probe on t124 since 4.11. What about to add stable tag for v4.11+
> here to unbreak stable kernels as well?

IOMMU node for host1x was added to t124 DT in kernel v4.14, so s/4.11/4.14/.