Re: [PATCH] tests/kms_writeback: refresh to expose writeback output

[Alex Hung <alex.hung@amd.com>]

On 2024-05-13 15:48, Abhinav Kumar wrote:
> 
> 
> On 5/13/2024 2:30 PM, Alex Hung wrote:
>> With dc2d7fb4f978, all kms_writeback subtests are skipped.
>>
>> Refresh the outputs to grab all supported connectors,
>> the writeback output that is just enabled.
>>
> 
> Can you please help to explain how the tests are getting skipped due to 
> setting the client_cap?
> 
> And also why calling igt_display_reset_outputs() is fixing this issue?

Without the igt_display_reset_outputs(), the result is

IGT-Version: 1.28-gbe9b99928 (x86_64) (Linux: 6.7.0-rc5-99-custom x86_64)
Using IGT_SRANDOM=1715637543 for randomisation
Opened device: /dev/dri/card0
Test requirement not met in function __igt_unique____real_main553, file 
../tests/kms_writeback.c:579:
Test requirement: output
Last errno: 95, Operation not supported
Subtest writeback-pixel-formats: SKIP (0.000s)
Subtest writeback-invalid-parameters: SKIP (0.000s)
Subtest writeback-fb-id: SKIP (0.000s)
Subtest writeback-fb-id-XRGB2101010: SKIP (0.000s)
Subtest writeback-check-output: SKIP (0.000s)
Subtest writeback-check-output-XRGB2101010: SKIP (0.000s)


It looks like the below "output = kms_writeback_get_output(&display)" 
will return null as it cannot find any connector type with 
DRM_MODE_CONNECTOR_WRITEBACK.

The igt_display_reset_outputs() is able to re-initialize the output and 
therefore includes the writeback output.

> 
>> Fixes: dc2d7fb4f978 ("lib/igt_kms: move setting 
>> DRM_CLIENT_CAP_WRITEBACK_CONNECTORS to kms_writeback")
>> Signed-off-by: Alex Hung <alex.hung@amd.com>
>> ---
>>   tests/kms_writeback.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/tests/kms_writeback.c b/tests/kms_writeback.c
>> index f89b2d62f..4c54f3b89 100644
>> --- a/tests/kms_writeback.c
>> +++ b/tests/kms_writeback.c
>> @@ -572,9 +572,11 @@ igt_main_args("b:c:f:dl", long_options, help_str, 
>> opt_handler, NULL)
>>           igt_require(display.is_atomic);
>>           ret = drmSetClientCap(display.drm_fd, 
>> DRM_CLIENT_CAP_WRITEBACK_CONNECTORS, 1);
>> -
> 
> Is this part needed for this patch?

No, but I think they are related and thus grouping them together is 
easier to read.

> 
>>           igt_require_f(!ret, "error setting 
>> DRM_CLIENT_CAP_WRITEBACK_CONNECTORS\n");
>> +        /* Refresh the outputs to grab all supported connectors.*/
>> +        igt_display_reset_outputs(&display);
>> +
>>           output = kms_writeback_get_output(&display);
>>           igt_require(output);