[Intel-gfx] [PATCH 3/4] drm/i915/perf: only append status when data is available

[Dixit, Ashutosh]

On Thu, 12 Mar 2020 16:05:01 -0700, Umesh Nerlige Ramappa wrote:
>
> From: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>
> The only bit of the status register we currently report in the
> i915-perf stream is the "report loss" bit. Only report this when we
> have some data to report with it. There was a kind of inconsistency
> here in that we could report report loss without appending the reports
> associated with the loss.

Splitting hair a bit, but I am wondering if this is realistic? If reports
have been lost in the middle of a OA buffer then there /will/ be some data
from the hardware so head != tail. So is the situation which this patch is
fixing ever been observed in practice?

Also, if we are doing this, how about moving the entire status handling
here, including intel_uncore_read() and OABUFFER_OVERFLOW handling (which I
understand resets the stream so probably doesn't have associated data).

In any case, since these are just random questions, this is:

Reviewed-by: Ashutosh Dixit <ashutosh.dixit at intel.com>