[PATCH] iommu/arm-smmu-v3: add tracepoints for cmdq_issue_cmdlist

[Will Deacon]

On Thu, Aug 27, 2020 at 09:33:51PM +1200, Barry Song wrote:
> cmdq_issue_cmdlist() is the hotspot that uses a lot of time. This patch
> adds tracepoints for it to help debug.
> 
> Signed-off-by: Barry Song <song.bao.hua at hisilicon.com>
> ---
>  * can furthermore develop an eBPF program to benchmark using this trace

Hmm, don't these things have a history of becoming ABI? If so, I don't
really want them in the driver at all, sorry. Do other drivers overcome
this somehow?

Will