[PATCH] tests/intel/xe_oa: Ignore other errors when looking for buffer overflow

[Umesh Nerlige Ramappa]

On Wed, May 21, 2025 at 01:12:28PM -0700, Dixit, Ashutosh wrote:
>On Tue, 20 May 2025 12:52:50 -0700, Umesh Nerlige Ramappa wrote:
>>
>> Occassionally other error bits will result in EIO and prematurely end
>> the buffer-fill test. For this test, ignore other errors.
>>
>> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4565
>
>From CI buglog it looks like, a REPORT_LOST (0x1) status is returned before
>BUFFER_OVERFLOW (0x2) status?

In this case yes, but I have seem other occurrences where counter 
overflow bit is set before buffer overflow.

>
>Patch generally looks ok, but a question below.
>
>
>> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
>> ---
>>  tests/intel/xe_oa.c | 17 +++++++++++------
>>  1 file changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/tests/intel/xe_oa.c b/tests/intel/xe_oa.c
>> index 73841a359daf..2022c5cb3955 100644
>> --- a/tests/intel/xe_oa.c
>> +++ b/tests/intel/xe_oa.c
>> @@ -2520,7 +2520,6 @@ test_buffer_fill(const struct drm_xe_engine_class_instance *hwe)
>>	char *buf = malloc(1024);
>>	bool overflow_seen;
>>	u32 oa_status;
>> -	int len;
>>
>>	igt_debug("oa_period %s\n", pretty_print_oa_period(oa_period));
>>	stream_fd = __perf_open(drm_fd, &param, true /* prevent_pm */);
>> @@ -2535,16 +2534,22 @@ test_buffer_fill(const struct drm_xe_engine_class_instance *hwe)
>>
>>	errno = 0;
>>	/* Read 0 bytes repeatedly until you see an EIO */
>> -	while ((len = read(stream_fd, buf, 0)) == -1 && (errno == EINTR || errno == ENOSPC)) {
>> +	while (-1 == read(stream_fd, buf, 0)) {
>> +		if (errno == EIO) {
>> +			oa_status = get_stream_status(stream_fd);
>> +			overflow_seen = oa_status & DRM_XE_OASTATUS_BUFFER_OVERFLOW;
>> +			if (overflow_seen)
>> +				break;
>> +		}
>>		usleep(100);
>>	}
>> -	igt_assert_eq(len, -1);
>> -	igt_assert_eq(errno, EIO);
>> +	igt_assert(overflow_seen);
>>
>> -	/* Ensure buffer overflowed */
>> +	/* Make sure the buffer overflow is cleared */
>> +	read(stream_fd, buf, 0);
>
>How does the buffer overflow status get cleared? We are still doing 0 size reads?

Hoping I understood what you are asking:

It would have been cleared as part of the read itself since the KMD 
implementation is doing a read-modify-write. Right? After that a 
subsequent read should have that bit set to 0.

The 0 size reads do not seem to affect the OA status update. So the KMD 
state should be pointing to the last values stored during read().

Regards,
Umesh
>
>>	oa_status = get_stream_status(stream_fd);
>>	overflow_seen = oa_status & DRM_XE_OASTATUS_BUFFER_OVERFLOW;
>> -	igt_assert(overflow_seen);
>> +	igt_assert_eq(overflow_seen, 0);
>>
>>	__perf_close(stream_fd);
>>  }
>> --
>> 2.43.0
>>
>
>Thanks.
>--
>Ashutosh