Re: [PATCH v5] drm/vkms: convert to use faux_device

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 01.07.25 um 12:49 schrieb Greg Kroah-Hartman:
> The vkms driver does not need to create a platform device, as there is
> no real platform resources associated it,  it only did so because it was
> simple to do that in order to get a device to use for resource
> management of drm resources.  Change the driver to use the faux device
> instead as this is NOT a real platform device.
>
> Tested-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
> Cc: Simona Vetter <simona@ffwll.ch>
> Cc: Melissa Wen <melissa.srw@gmail.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: David Airlie <airlied@gmail.com>
> Cc: dri-devel@lists.freedesktop.org
> Reviewed-by: Lyude Paul <lyude@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> v5: - rebased against 6.16-rc4
>      - added reviewed-by and tested-by lines
>      - was somehow dropped from drm trees, resending to make sure it
>        isn't lost

Also see my comment in the vgem change. The patches will go in soon 
after "drm/gem-shmem: Do not map s/g table by default". [1] Thanks for 
the update.

Best regards
Thomas

[1] https://patchwork.freedesktop.org/series/150968/

>
> v4: - first version of the patch, was part of a larger patch series that
>        has been mostly all applied to the tree.
>
>   drivers/gpu/drm/vkms/vkms_drv.c | 28 ++++++++++++++--------------
>   drivers/gpu/drm/vkms/vkms_drv.h |  4 ++--
>   2 files changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index a24d1655f7b8..e8472d9b6e3b 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -10,7 +10,7 @@
>    */
>   
>   #include <linux/module.h>
> -#include <linux/platform_device.h>
> +#include <linux/device/faux.h>
>   #include <linux/dma-mapping.h>
>   
>   #include <drm/clients/drm_client_setup.h>
> @@ -149,27 +149,27 @@ static int vkms_modeset_init(struct vkms_device *vkmsdev)
>   static int vkms_create(struct vkms_config *config)
>   {
>   	int ret;
> -	struct platform_device *pdev;
> +	struct faux_device *fdev;
>   	struct vkms_device *vkms_device;
>   	const char *dev_name;
>   
>   	dev_name = vkms_config_get_device_name(config);
> -	pdev = platform_device_register_simple(dev_name, -1, NULL, 0);
> -	if (IS_ERR(pdev))
> -		return PTR_ERR(pdev);
> +	fdev = faux_device_create(dev_name, NULL, NULL);
> +	if (!fdev)
> +		return -ENODEV;
>   
> -	if (!devres_open_group(&pdev->dev, NULL, GFP_KERNEL)) {
> +	if (!devres_open_group(&fdev->dev, NULL, GFP_KERNEL)) {
>   		ret = -ENOMEM;
>   		goto out_unregister;
>   	}
>   
> -	vkms_device = devm_drm_dev_alloc(&pdev->dev, &vkms_driver,
> +	vkms_device = devm_drm_dev_alloc(&fdev->dev, &vkms_driver,
>   					 struct vkms_device, drm);
>   	if (IS_ERR(vkms_device)) {
>   		ret = PTR_ERR(vkms_device);
>   		goto out_devres;
>   	}
> -	vkms_device->platform = pdev;
> +	vkms_device->faux_dev = fdev;
>   	vkms_device->config = config;
>   	config->dev = vkms_device;
>   
> @@ -203,9 +203,9 @@ static int vkms_create(struct vkms_config *config)
>   	return 0;
>   
>   out_devres:
> -	devres_release_group(&pdev->dev, NULL);
> +	devres_release_group(&fdev->dev, NULL);
>   out_unregister:
> -	platform_device_unregister(pdev);
> +	faux_device_destroy(fdev);
>   	return ret;
>   }
>   
> @@ -231,19 +231,19 @@ static int __init vkms_init(void)
>   
>   static void vkms_destroy(struct vkms_config *config)
>   {
> -	struct platform_device *pdev;
> +	struct faux_device *fdev;
>   
>   	if (!config->dev) {
>   		DRM_INFO("vkms_device is NULL.\n");
>   		return;
>   	}
>   
> -	pdev = config->dev->platform;
> +	fdev = config->dev->faux_dev;
>   
>   	drm_dev_unregister(&config->dev->drm);
>   	drm_atomic_helper_shutdown(&config->dev->drm);
> -	devres_release_group(&pdev->dev, NULL);
> -	platform_device_unregister(pdev);
> +	devres_release_group(&fdev->dev, NULL);
> +	faux_device_destroy(fdev);
>   
>   	config->dev = NULL;
>   }
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index a74a7fc3a056..5a46016e1890 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -197,13 +197,13 @@ struct vkms_config;
>    * struct vkms_device - Description of a VKMS device
>    *
>    * @drm - Base device in DRM
> - * @platform - Associated platform device
> + * @faux_dev - Associated faux device
>    * @output - Configuration and sub-components of the VKMS device
>    * @config: Configuration used in this VKMS device
>    */
>   struct vkms_device {
>   	struct drm_device drm;
> -	struct platform_device *platform;
> +	struct faux_device *faux_dev;
>   	const struct vkms_config *config;
>   };
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)