Re: [PATCH v2 13/33] drm/client: Add some tests for drm_connector_pick_cmdline_mode()

[Javier Martinez Canillas]

On 9/23/22 11:15, Thomas Zimmermann wrote:
> Hi
> 
> Am 22.09.22 um 16:25 schrieb Maxime Ripard:
>> drm_connector_pick_cmdline_mode() is in charge of finding a proper
>> drm_display_mode from the definition we got in the video= command line
>> argument.
>>
>> Let's add some unit tests to make sure we're not getting any regressions
>> there.
>>
>> Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
>>
>> diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
>> index bbc535cc50dd..d553e793e673 100644
>> --- a/drivers/gpu/drm/drm_client_modeset.c
>> +++ b/drivers/gpu/drm/drm_client_modeset.c
>> @@ -1237,3 +1237,7 @@ int drm_client_modeset_dpms(struct drm_client_dev *client, int mode)
>>   	return ret;
>>   }
>>   EXPORT_SYMBOL(drm_client_modeset_dpms);
>> +
>> +#ifdef CONFIG_DRM_KUNIT_TEST
>> +#include "tests/drm_client_modeset_test.c"
>> +#endif
> 
> I strongly dislike this style of including source files in each other. 
> It's a recipe for all kind of build errors. Can you do something else?
>

This seems to be the convention used to test static functions and what's
documented in the Kunit docs: https://kunit.dev/third_party/kernel/docs/tips.html#testing-static-functions

I agree with you that's not ideal but I think that consistency with how
it is done by other subsystems is also important.
 
> As the tested function is an internal interface, maybe export a wrapper 
> if tests are enabled, like this:
> 
> #ifdef CONFIG_DRM_KUNIT_TEST
> struct drm_display_mode *
> drm_connector_pick_cmdline_mode_kunit(drm_conenctor)
> {
>    return drm_connector_pick_cmdline_mode(connector)
> }
> EXPORT_SYMBOL(drm_connector_pick_cmdline_mode_kunit)
> #endif
> 
> The wrapper's declaration can be located in the kunit test file.
> 

But that's also not nice since we are artificially exposing these only
to allow the static functions to be called from unit tests. And would
be a different approach than the one used by all other subsystems...

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat