Re: [PATCH 2/2] drm: add DRIVER_RENDER_ONLY

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 11.10.22 um 13:04 schrieb Christian König:
> This allows to suppress creating the primary node. Useful for drivers
> which don't expose any display functionality, but are render only by
> design.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
>   drivers/gpu/drm/drm_drv.c   | 10 ++++++----
>   drivers/gpu/drm/drm_prime.c |  2 +-
>   include/drm/drm_drv.h       |  7 +++++++
>   3 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index d81783f43452..4a525f78a932 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -634,9 +634,11 @@ static int drm_dev_init(struct drm_device *dev,
>   			goto err;
>   	}
>   
> -	ret = drm_minor_alloc(dev, DRM_MINOR_PRIMARY);
> -	if (ret)
> -		goto err;
> +	if (!drm_core_check_feature(dev, DRIVER_RENDER_ONLY)) {
> +		ret = drm_minor_alloc(dev, DRM_MINOR_PRIMARY);
> +		if (ret)
> +			goto err;
> +	}
>   
>   	ret = drm_legacy_create_map_hash(dev);
>   	if (ret)
> @@ -902,7 +904,7 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>   		 driver->name, driver->major, driver->minor,
>   		 driver->patchlevel, driver->date,
>   		 dev->dev ? dev_name(dev->dev) : "virtual device",
> -		 dev->primary->index);
> +		 (dev->primary ?: dev->render)->index);
>   
>   	goto out_unlock;
>   
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index a3f180653b8b..4afd3f15b135 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -740,7 +740,7 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>   	}
>   
>   	/* Used by drm_gem_mmap() to lookup the GEM object */
> -	priv->minor = obj->dev->primary;
> +	priv->minor = obj->dev->primary ?: obj->dev->render;
>   	fil->private_data = priv;
>   
>   	ret = drm_vma_node_allow(&obj->vma_node, priv);
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index f6159acb8856..0a1450d47ca2 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -94,6 +94,13 @@ enum drm_driver_feature {
>   	 * synchronization of command submission.
>   	 */
>   	DRIVER_SYNCOBJ_TIMELINE         = BIT(6),
> +	/**
> +	 * @DRIVER_RENDER_ONLY
> +	 *
> +	 * Driver is a render node only driver and don't want to support the
> +	 * primary interface.
> +	 */
> +	DRIVER_RENDER_ONLY		= BIT(7),

Is it really necessary to add a new flag?  If a driver sets DRIVER_GEM 
and omits DRIVER_MODESET wouldn't this have the same meaning?

Best regards
Thomas

>   
>   	/* IMPORTANT: Below are all the legacy flags, add new ones above. */
>   

--
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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