[PATCH 5/6] iommu/arm-smmu: support buggy implementations with invalidate-on-map

On Wed, Nov 12 2014 at 10:26:43 AM, Will Deacon [off-list ref] wrote:

Hi Mitch,

On Wed, Aug 13, 2014 at 01:51:38AM +0100, Mitchel Humpherys wrote:

quoted

Add a workaround for some buggy hardware that requires a TLB invalidate
operation to occur at map time. Activate the feature with the
qcom,smmu-invalidate-on-map boolean DT property.

I'm digging up an old thread here, but I've been working on a new page-table
allocator for the SMMU and looked into implementing this workaround for you
in there. When I do the TLBI on map after installing the new PTE, can I just
invalidate the range mapped by that PTE, or does it need to be a full TLBI?

I'm not totally sure on the history of the hardware errata but I believe
it's just the range mapped by that pte.  We use SMMU_CBn_TLBIVA in the
our smmu driver.

However, let's actually just drop this...  It's looking like the targets
we have that will use the arm-smmu driver thankfully won't need this
workaround.  Thanks for keeping this in mind though :)


-Mitch

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project