Re: [PATCH i-g-t] tests/intel/xe_oa: Extend enable-disable to read after disabling stream

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Mon, 30 Mar 2026 10:58:57 -0700, Umesh Nerlige Ramappa wrote:
>
> On Tue, Mar 17, 2026 at 03:39:10PM -0700, Ashutosh Dixit wrote:
> > Extend enable-disable subtest to validate the new feature of reading after
> > disabling OA stream.
> >
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
>
> LGTM,
>
> Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>

Thanks Umesh, but if you see Xe.CI.FULL results, the test actually
fails. See below.

> > ---
> > tests/intel/xe_oa.c | 25 +++++++++++++++++++++++++
> > 1 file changed, 25 insertions(+)
> >
> > diff --git a/tests/intel/xe_oa.c b/tests/intel/xe_oa.c
> > index 387f29535e..6a602a014c 100644
> > --- a/tests/intel/xe_oa.c
> > +++ b/tests/intel/xe_oa.c
> > @@ -2774,6 +2774,31 @@ test_enable_disable(const struct drm_xe_oa_unit *oau)
> >	get_stream_status(stream_fd);
> >	igt_assert_eq(ret, sizeof(buf));
> >
> > +	/*
> > +	 * Wait again for number of reports specified in
> > +	 * DRM_XE_OA_PROPERTY_WAIT_NUM_REPORTS
> > +	 */
> > +	pollfd.fd = stream_fd;
> > +	pollfd.events = POLLIN;
> > +	poll(&pollfd, 1, -1);
> > +	igt_assert(pollfd.revents & POLLIN);
> > +
> > +	do_ioctl(stream_fd, DRM_XE_OBSERVATION_IOCTL_DISABLE, 0);
> > +
> > +	/* Ensure num_reports can be read even with disabled stream */
> > +	while ((ret = read(stream_fd, buf, sizeof(buf))) < 0 && errno == EINTR)
> > +		;
> > +	get_stream_status(stream_fd);
> > +	igt_assert_eq(ret, sizeof(buf));

The failure is here, where we sometimes see 1 report instead of 5
(wait_num_reports is 5). I finally figured out how it could happen.

Let's say 6 reports were available in the *previous* read (before disabling
the stream). Now if we read with a buffer size of 5 reports, in the kernel
pollin would remain set. So when we read the next time we only will read 1
report.

To get around this I have changed the above assert to just 'igt_assert(ret >
0)' basically:

	igt_assert_lt(0, ret);

Thanks.
--
Ashutosh



> > +
> > +	/* In non-blocking mode read till we see a -EAGAIN, signifying all available data is read */
> > +	set_fd_flags(stream_fd, O_CLOEXEC | O_NONBLOCK);
> > +	while ((ret = read(stream_fd, buf, sizeof(buf))) > 0 ||
> > +	       (ret == -1 && (errno == EINTR || errno == EIO)))
> > +		;
> > +	igt_assert_eq(ret, -1);
> > +	igt_assert_eq(errno, EAGAIN);
> > +
> >	__perf_close(stream_fd);
> > }
> >
> > --
> > 2.48.1
> >