[PATCH v3] Return only active connectors for get_resources ioctl

[Jani Nikula]

On Thu, 29 Nov 2018, Stanislav Lisovskiy <stanislav.lisovskiy at intel.com> wrote:
> Currently kernel might allocate different connector ids
> for the same outputs in case of DP MST, which seems to
> confuse userspace. There are can be different connector
> ids in the list, which could be assigned to the same
> output, while being in different states.
> This results in issues, like external displays staying
> blank after quick unplugging and plugging back(bug #106250).
> Returning only active DP connectors fixes the issue.

Some nitpicks here...

The patch subject lacks a prefix.

>
> v2: Removed caps from the title
>
> v3: Refactored initial condition to look more compact.
>     Thanks to Chris Wilson for giving a hint.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106250
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> ---
>  drivers/gpu/drm/drm_mode_config.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index ee80788f2c40..3e2cd959a66a 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -143,22 +143,28 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
>  	drm_connector_list_iter_begin(dev, &conn_iter);
>  	count = 0;
>  	connector_id = u64_to_user_ptr(card_res->connector_id_ptr);
> +	DRM_DEBUG_KMS("GetResources: writing connectors start");

I think the added debugs here are too verbose. You should probably
separate the debugs from the actual change here.

Note also that the logging functions already add the function name, so
"GetResources:" is redundant. Also "\n" is missing.

>  	drm_for_each_connector_iter(connector, &conn_iter) {
>  		/* only expose writeback connectors if userspace understands them */
>  		if (!file_priv->writeback_connectors &&
>  		    (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK))
>  			continue;
>  
> +		if (READ_ONCE(connector->registration_state) != DRM_CONNECTOR_REGISTERED)
> +			continue;
> +
>  		if (drm_lease_held(file_priv, connector->base.id)) {
>  			if (count < card_res->count_connectors &&
>  			    put_user(connector->base.id, connector_id + count)) {
>  				drm_connector_list_iter_end(&conn_iter);
>  				return -EFAULT;
>  			}
> +			DRM_DEBUG_KMS("GetResources: connector %s", connector->name);

Please look around, the connector logging is fairly consistent
throughout.

BR,
Jani.

>  			count++;
>  		}
>  	}
>  	card_res->count_connectors = count;
> +	DRM_DEBUG_KMS("GetResources: writing connectors end - count %d", count);
>  	drm_connector_list_iter_end(&conn_iter);
>  
>  	return ret;

-- 
Jani Nikula, Intel Open Source Graphics Center