linux-kernel - Re: [RESEND PATCH 4/5] drm: Add a drm_drv

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Date:   Wed, 03 Nov 2021 15:41:00 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Javier Martinez Canillas <javierm@...hat.com>,
        linux-kernel@...r.kernel.org
Cc:     Pekka Paalanen <pekka.paalanen@...labora.com>,
        dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Michel Dänzer <michel@...nzer.net>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Peter Robinson <pbrobinson@...il.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Neal Gompa <ngompa13@...il.com>
Subject: Re: [RESEND PATCH 4/5] drm: Add a drm_drv_enabled() helper function

On Wed, 03 Nov 2021, Javier Martinez Canillas <javierm@...hat.com> 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@...e.de>
> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>

Can't see i915 trivially using this due to the drm_driver
parameter. Please let's not merge helpers like this without actual
users.

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

-- 
Jani Nikula, Intel Open Source Graphics Center