[Intel-gfx] [PATCH 2/5] drm/i915/guc: do not dump execlists state with GuC submission

[Chris Wilson]

Quoting Daniele Ceraolo Spurio (2021-01-06 17:21:16)
> 
> 
> On 1/5/2021 6:55 PM, Chris Wilson wrote:
> > Quoting Daniele Ceraolo Spurio (2021-01-06 02:32:28)
> >>
> >> On 1/5/2021 4:58 PM, Chris Wilson wrote:
> >>> Quoting Daniele Ceraolo Spurio (2021-01-05 23:19:44)
> >>>> GuC owns the execlists state and the context IDs used for submission, so
> >>>> the status of the ports and the CSB entries are not something we control
> >>>> or can decode from the i915 side, therefore we can avoid dumping it. A
> >>>> follow-up patch will also stop setting the csb pointers when using GuC
> >>>> submission.
> >>>>
> >>>> GuC dumps all the required events in the GuC logs when verbosity is set
> >>>> high enough.
> >>> Would not be worth including, or is it not very helpful for debugging
> >>> curious engine stalls?
> >> GuC is going to reset the engine if it stalls, so we should get the GuC
> >> logs and the engine state included in the error state.
> > Here we would be focusing on "why hasn't a request been submitted/executed".
> > A bad request is usually self-evident, but a missing one is tricky.
> 
> Agreed, but I still don't think we could use the CSB info even if we 
> dumped it. We currently can't map CSB events in GuC submission mode to 
> specific contexts, because the ctx IDs used by the GuC do not map to the 
> ones used by i915. We've asked the GuC team to expose a way to do such a 
> mapping, but that's still under discussion. In the meantime we plan to 
> add a few traces to make sure the requests reach the GuC and use the GuC 
> logs for what goes on inside the FW (GuC logs include the context IDs it 
> uses for submission and all CSB events on high verbosity).

I was more reflecting on what could be here instead. Details of the ctb?
It would be great to have a snapshot of some relevant guc state, merely
wonder if we could extract anything from the log automatically. As well
as the usual what have we submitted to the guc.
-Chris