Re: [PATCH v3 02/10] drm/client: Add hotplug_failed flag

[Sam Ravnborg <sam@ravnborg.org>]

Hi Thomas,

On Wed, Jan 25, 2023 at 09:04:07PM +0100, Thomas Zimmermann wrote:
> Signal failed hotplugging with a flag in struct drm_client_dev. If set,
> the client helpers will not further try to set up the fbdev display.
> 
> This used to be signalled with a combination of cleared pointers in
> struct drm_fb_helper,
I failed to find where we clear the pointers. What do I miss?
(I had assumed we would stop clearing the pointers after this change).

	Sam

which prevents us from initializing these pointers
> early after allocation.
> 
> The change also harmonizes behavior among DRM clients. Additional DRM
> clients will now handle failed hotplugging like fbdev does.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> ---
>  drivers/gpu/drm/drm_client.c        | 5 +++++
>  drivers/gpu/drm/drm_fbdev_generic.c | 4 ----
>  include/drm/drm_client.h            | 8 ++++++++
>  3 files changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
> index 09ac191c202d..009e7b10455c 100644
> --- a/drivers/gpu/drm/drm_client.c
> +++ b/drivers/gpu/drm/drm_client.c
> @@ -208,8 +208,13 @@ void drm_client_dev_hotplug(struct drm_device *dev)
>  		if (!client->funcs || !client->funcs->hotplug)
>  			continue;
>  
> +		if (client->hotplug_failed)
> +			continue;
> +
>  		ret = client->funcs->hotplug(client);
>  		drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
> +		if (ret)
> +			client->hotplug_failed = true;
>  	}
>  	mutex_unlock(&dev->clientlist_mutex);
>  }
> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
> index 3d455a2e3fb5..135d58b8007b 100644
> --- a/drivers/gpu/drm/drm_fbdev_generic.c
> +++ b/drivers/gpu/drm/drm_fbdev_generic.c
> @@ -382,10 +382,6 @@ static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
>  	struct drm_device *dev = client->dev;
>  	int ret;
>  
> -	/* Setup is not retried if it has failed */
> -	if (!fb_helper->dev && fb_helper->funcs)
> -		return 0;
> -
>  	if (dev->fb_helper)
>  		return drm_fb_helper_hotplug_event(dev->fb_helper);
>  
> diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
> index 4fc8018eddda..39482527a775 100644
> --- a/include/drm/drm_client.h
> +++ b/include/drm/drm_client.h
> @@ -106,6 +106,14 @@ struct drm_client_dev {
>  	 * @modesets: CRTC configurations
>  	 */
>  	struct drm_mode_set *modesets;
> +
> +	/**
> +	 * @hotplug failed:
> +	 *
> +	 * Set by client hotplug helpers if the hotplugging failed
> +	 * before. It is usually not tried again.
> +	 */
> +	bool hotplug_failed;
>  };
>  
>  int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
> -- 
> 2.39.0