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

[Vincent Knecht]

Le jeudi 26 mai 2022 à 09:44 +0530, Sai Prakash Ranjan a écrit :
> 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(-)

Hi Sai, and thanks for this patch !

I've encountered TLB sync timeouts with msm8939 SoC recently.
What would be needed to add to this patch so this SoC is supported ?
Like, where could one check the values to be used in an equivalent
of qcom_smmu_impl0_reg_offset values for this SoC (if any change needed) ?
Current values are not found by simply greping in downstream/vendor dtsi/dts files...