On Mon, May 22, 2023 at 02:50:51PM -0700, Dixit, Ashutosh wrote:
On Mon, 22 May 2023 14:34:18 -0700, Umesh Nerlige Ramappa wrote:
On Mon, May 22, 2023 at 01:17:49PM -0700, Ashutosh Dixit wrote:
> Clearing out report id and timestamp as means to detect unlanded reports
> only works if report size is power of 2. That is, only when report size is
> a sub-multiple of the OA buffer size can we be certain that reports will
> land at the same place each time in the OA buffer (after rewind). If report
> size is not a power of 2, we need to zero out the entire report to be able
> to detect unlanded reports reliably.
>
> Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_perf.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 19d5652300eeb..58284156428dc 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -877,12 +877,17 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
> stream->oa_buffer.last_ctx_id = ctx_id;
> }
>
> - /*
> - * Clear out the report id and timestamp as a means to detect unlanded
> - * reports.
> - */
> - oa_report_id_clear(stream, report32);
> - oa_timestamp_clear(stream, report32);
> + if (is_power_of_2(report_size)) {
> + /*
> + * Clear out the report id and timestamp as a means
> + * to detect unlanded reports.
> + */
> + oa_report_id_clear(stream, report32);
> + oa_timestamp_clear(stream, report32);
> + } else {
> + /* Zero out the entire report */
> + memset(report32, 0, report_size);
Indeed, this was a bug. For a minute, I started wondering if this is the
issue I am running into with the other patch posted for DG2, but then I see
the issue within the first fill of the OA buffer where chunks of the
reports are zeroed out, so this is a new issue.
Yes I saw this while reviewing your patch. And also I thought your issue
was happening on DG2 with power of 2 report size, only on MTL OAM we
introduce non power of 2 report size.
lgtm,
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
Maybe this should include Fixes: tag pointing to the patch that
introduced the OAM non-power-of-2 format.
Umesh
Thanks.
--
Ashutosh
> + }
> }
>
> if (start_offset != *offset) {
> --
> 2.38.0
>
