On Thu, Oct 24, 2019 at 11:51:51AM +0100, Will Deacon wrote:
> Hi all,
>
> In commit 90ec7a76cc4b ("iommu/io-pgtable-arm: Add support to use system
> cache") we added support for IOMMU_QCOM_SYS_CACHE which was merged into 5.3.
> This allows non-coherent devices to request an outer cacheable memory
> type.... except that nobody actually does this in mainline. I remember there
> being a potential DRM user but I don't know what happened to it.
You are thinking of:
https://lore.kernel.org/linux-arm-msm/[email protected]/
That is still a thing but it never got revisited after 5.3. I believe that
Sharat will have a refresh coming soon.
> Given that this isn't actually exposed in the DMA API, I worry that we're
> just carrying part of an out-of-tree hack here and propose that we drop
> the flag altogether unless we get an upstream user, preferably by plumbing
> this into the DMA API via a new attribute.
I wouldn't mind if you plumbed it into the DMA API as well but I would ask to
keep an alternate path for those of us who make our own way.
Jordan
--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
_______________________________________________
iommu mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/iommu
