Re: [PATCHv2] iommu/arm-smmu-qcom: Add debug support for TLB sync timeouts

[Sai Prakash Ranjan]

On 7/6/2022 5:26 PM, Will Deacon wrote:
> On Thu, May 26, 2022 at 09:44:03AM +0530, Sai Prakash Ranjan wrote:
> > TLB sync timeouts can be due to various reasons such as TBU power down
> > or pending TCU/TBU invalidation/sync and so on. Debugging these often
> > require dumping of some implementation defined registers to know the
> > status of TBU/TCU operations and some of these registers are not
> > accessible in non-secure world such as from kernel and requires SMC
> > calls to read them in the secure world. So, add this debug support
> > to dump implementation defined registers for TLB sync timeout issues.
> >
> > Signed-off-by: Sai Prakash Ranjan <quic_saipraka@xxxxxxxxxxx>
> > ---
> >
> > Changes in v2:
> >   * Use scm call consistently so that it works on older chipsets where
> >     some of these regs are secure registers.
> >   * Add device specific data to get the implementation defined register
> >     offsets.
> >
> > ---
> >   drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 161 ++++++++++++++++++---
> >   drivers/iommu/arm/arm-smmu/arm-smmu.c      |   2 +
> >   drivers/iommu/arm/arm-smmu/arm-smmu.h      |   1 +
> >   3 files changed, 146 insertions(+), 18 deletions(-)
> If this is useful to you, then I suppose it's something we could support,
> however I'm pretty worried about our ability to maintain/scale this stuff
> as it is extended to support additional SoCs and other custom debugging
> features.
>
> Perhaps you could stick it all in arm-smmu-qcom-debug.c and have a new
> config option for that, so at least it's even further out of the way?
>
> Will

Sounds good to me, will do that.

Thanks,
Sai