Re: [RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

[Thomas Zimmermann]

Hi

Am 03.11.21 um 14:41 schrieb Jani Nikula:
> On Wed, 03 Nov 2021, Javier Martinez Canillas <javierm@xxxxxxxxxx> wrote:
> > DRM drivers can use this to determine whether they can be enabled or not.
> >
> > For now it's just a wrapper around drm_modeset_disabled() but having the
> > indirection level will allow to add other conditions besides "nomodeset".
> >
> > Suggested-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
>
> Can't see i915 trivially using this due to the drm_driver
> parameter. Please let's not merge helpers like this without actual
> users.

Can you explain?

This would be called on the top of the PCI probe function. The parameter 
would allow to decide on a per-driver base (e.g., to ignore generic 
drivers).

Best regards
Thomas

> BR,
> Jani.
>
>
> > ---
> >
> >   drivers/gpu/drm/drm_drv.c | 21 +++++++++++++++++++++
> >   include/drm/drm_drv.h     |  1 +
> >   2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> > index 8214a0b1ab7f..70ef08941e06 100644
> > --- a/drivers/gpu/drm/drm_drv.c
> > +++ b/drivers/gpu/drm/drm_drv.c
> > @@ -975,6 +975,27 @@ int drm_dev_set_unique(struct drm_device *dev, const char *name)
> >   }
> >   EXPORT_SYMBOL(drm_dev_set_unique);
> >   
> > +/**
> > + * drm_drv_enabled - Checks if a DRM driver can be enabled
> > + * @driver: DRM driver to check
> > + *
> > + * Checks whether a DRM driver can be enabled or not. This may be the case
> > + * if the "nomodeset" kernel command line parameter is used.
> > + *
> > + * Returns:
> > + * True if the DRM driver is enabled and false otherwise.
> > + */
> > +bool drm_drv_enabled(const struct drm_driver *driver)
> > +{
> > +	if (drm_modeset_disabled()) {
> > +		DRM_INFO("%s driver is disabled\n", driver->name);
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +EXPORT_SYMBOL(drm_drv_enabled);
> > +
> >   /*
> >    * DRM Core
> >    * The DRM core module initializes all global DRM objects and makes them
> > diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> > index 0cd95953cdf5..48f2b6eec012 100644
> > --- a/include/drm/drm_drv.h
> > +++ b/include/drm/drm_drv.h
> > @@ -598,5 +598,6 @@ static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
> >   
> >   int drm_dev_set_unique(struct drm_device *dev, const char *name);
> >   
> > +bool drm_drv_enabled(const struct drm_driver *driver);
> >   
> >   #endif

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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