Re: [PATCH] iommu/dma: Add support for DMA_ATTR_SYS_CACHE

[isaacm]

On 2019-10-25 22:30, Christoph Hellwig wrote:
> The definition makes very little sense.
Can you please clarify what part doesnât make sense, and why? This is 
really just an extension of this patch that got mainlined, so that 
clients that use the DMA API can use IOMMU_QCOM_SYS_CACHE as well: 
https://patchwork.kernel.org/patch/10946099/
>  Any without a user in the same series it is a complete no-go anyway.
IOMMU_QCOM_SYS_CACHE does not have any current users in the mainline, 
nor did it have it in the patch series in which it got merged, yet it is 
still present? Furthermore, there are plans to upstream support for one 
of our SoCs that may benefit from this, as seen here: 
https://www.spinics.net/lists/iommu/msg39608.html.

Thanks,
Isaac