On 2021-01-07 02:45, chenxiang (M) wrote:
Hi Will, Robin or other guys,
When debugging SMMU/SVA issue on huawei ARM64 board, we find that it
lacks of enough debugfs for ARM SMMU driver (such as
the value of STE/CD which we need to check sometimes). Currently it
creates top-level iommu directory in debugfs, but there is no debugfs
for ARM SMMU driver specially. Do you know whether ARM have the plan to
do that recently?
FWIW I don't think I've ever felt the need to need to inspect the Stream
Table on a live system. So far the nature of the STE code has been
simple enough that it's very hard for any given STE to be *wrong* -
either it's set up as expected and thus works fine, or it's not
initialised at all and you get C_BAD_STE, where 99% of the time you then
just cross-reference the Stream ID against the firmware and find that
the DT/IORT is wrong.
Similarly I don't think I've even even *seen* an issue that could be
attributed to a context descriptor, although I appreciate that as we
start landing more PASID and SVA support the scope for that starts to
widen considerably.
Feel free to propose a patch if you believe it would be genuinely useful
and won't just bit-rot into a maintenance burden, but it's not something
that's on our roadmap here.
Thanks,
Robin.
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