Re: [PATCH] drm/virtgpu: Add PM support for suspend/resume

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 01.04.26 um 08:10 schrieb Morris Pan:
> Add freeze/restore callbacks to handle system suspend/resume.
> During freeze, delete virtqueues and reset device.
> During restore, reinitialize virtqueues and mark device ready.
>
> Signed-off-by: Morris Pan <morris.pan@mediatek.com>
> ---
>   drivers/gpu/drm/virtio/virtgpu_drv.c | 40 +++++++++++++++++++++++++++-
>   1 file changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
> index a5ce96fb8a1d..fbca0a82958c 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
> @@ -145,6 +145,40 @@ static void virtio_gpu_config_changed(struct virtio_device *vdev)
>   	schedule_work(&vgdev->config_changed_work);
>   }
>   
> +#ifdef CONFIG_PM_SLEEP
> +static int virtgpu_freeze(struct virtio_device *vdev)
> +{

I think you first need to call drm_mode_config_helper_suspend() [1] to 
stop DRM and save the current state.

[1] 
https://elixir.bootlin.com/linux/v6.19.10/source/drivers/gpu/drm/drm_modeset_helper.c#L179

> +	vdev->config->del_vqs(vdev);
> +	virtio_reset_device(vdev);
> +
> +	return 0;
> +}
> +
> +static int virtgpu_restore(struct virtio_device *vdev)
> +{
> +	int ret;
> +	struct virtqueue *vqs[2];
> +	struct drm_device *dev = vdev->priv;
> +	struct virtio_gpu_device *vgdev = dev->dev_private;
> +	struct virtqueue_info vqs_info[] = {
> +		{ "control", virtio_gpu_ctrl_ack },
> +		{ "cursor", virtio_gpu_cursor_ack },
> +	};
> +
> +	ret = virtio_find_vqs(vdev, 2, vqs, vqs_info, NULL);
> +	if (ret) {
> +		DRM_ERROR("failed to find virtio queues\n");
> +		return ret;
> +	}
> +
> +	vgdev->ctrlq.vq = vqs[0];
> +	vgdev->cursorq.vq = vqs[1];
> +	virtio_device_ready(vdev);

And here you have to call drm_mode_config_helper_resume() [2] to restore 
the DRM state from before the freeze.

[2] 
https://elixir.bootlin.com/linux/v6.19.10/source/drivers/gpu/drm/drm_modeset_helper.c#L227

Best regards
Thomas

> +
> +	return 0;
> +}
> +#endif
> +
>   static struct virtio_device_id id_table[] = {
>   	{ VIRTIO_ID_GPU, VIRTIO_DEV_ANY_ID },
>   	{ 0 },
> @@ -172,7 +206,11 @@ static struct virtio_driver virtio_gpu_driver = {
>   	.probe = virtio_gpu_probe,
>   	.remove = virtio_gpu_remove,
>   	.shutdown = virtio_gpu_shutdown,
> -	.config_changed = virtio_gpu_config_changed
> +	.config_changed = virtio_gpu_config_changed,
> +#ifdef CONFIG_PM_SLEEP
> +	.freeze = virtgpu_freeze,
> +	.restore = virtgpu_restore
> +#endif
>   };
>   
>   static int __init virtio_gpu_driver_init(void)

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)