Re: [PATCH v3 5/6] drm/probe-helper: use drm_kms_helper_connector_hotplug_event

[Sam Ravnborg <sam@ravnborg.org>]

Hi Simon,

On Fri, Oct 15, 2021 at 04:33:45PM +0000, Simon Ser wrote:
> If an hotplug event only updates a single connector, use
> drm_kms_helper_connector_hotplug_event instead of
> drm_kms_helper_hotplug_event.
> 
> Signed-off-by: Simon Ser <contact@emersion.fr>
> ---
>  drivers/gpu/drm/drm_probe_helper.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 3aef3b188c99..6049dc92324b 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -927,7 +927,7 @@ EXPORT_SYMBOL(drm_connector_helper_hpd_irq_event);
>   */
>  bool drm_helper_hpd_irq_event(struct drm_device *dev)
>  {
> -	struct drm_connector *connector;
> +	struct drm_connector *connector, *changed_connector = NULL;
>  	struct drm_connector_list_iter conn_iter;
>  	bool changed = false;
>  
> @@ -941,15 +941,27 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
>  		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
>  			continue;
>  
> -		if (check_connector_changed(connector))
> +		if (check_connector_changed(connector)) {
> +			if (changed) {
> +				if (changed_connector)
> +					drm_connector_put(changed_connector);
> +				changed_connector = NULL;
> +			} else {
> +				drm_connector_get(connector);
> +				changed_connector = connector;
> +			}
This code is a little confusing to read.

In case we have only one connector with a change we hit the else part.
What we really want to find out is if we have one or more connectors
with a change.
We could do something like:

	struct drm_connector *changed_connector = NULL;
	int changes = 0;


	...

	/* Find if we have one or more changed connectors */
	drm_for_each_connector_iter(connector, &conn_iter) {
		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
			continue;

		if (check_connector_changed(connector)) {
			if (!changes) {
				changed_connector = connector;
				drm_connector_get(changed_connector);
			}

			changes++;
		}
	}
	drm_connector_list_iter_end(&conn_iter);
	mutex_unlock(&dev->mode_config.mutex);

	if (changes == 1)
		drm_kms_helper_connector_hotplug_event(changed_connector);
	else if (changes > 1)
		drm_kms_helper_hotplug_event(dev);

	if (changed_connector)
		drm_connector_put(changed_connector);


Maybe the only reason why I think this is better is bc I wrote it?!?

	Sam