linux-kernel - Re: [PATCH 2/4 v2] drm: introduce drm_connector_register

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Message-ID: <3480153.fsvGkg3hVW@avalon>
Date:	Mon, 21 Mar 2016 15:33:13 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	dri-devel@...ts.freedesktop.org
Cc:	Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4 v2] drm: introduce drm_connector_register_all() helper

Hi Alexey,

Thank you for the patch.

On Monday 21 Mar 2016 15:28:38 Alexey Brodkin wrote:
> As a pair to already existing drm_connector_unregister_all() we're adding
> generic implementation of what is already done in some drivers.
> 
> Once this helper is implemented we'll be ready to switch existing
> driver-specific implementations with the generic one.
> 
> Signed-off-by: Alexey Brodkin <abrodkin@...opsys.com>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: David Airlie <airlied@...ux.ie>
> ---
> 
> Changes v1 -> v2:
>  * Rename drm_connector_unplug_all() to drm_connector_unregister_all()
>  * Use drm_for_each_connector() instead of list_for_each_entry()
>  * Updated kerneldoc for drm_dev_register()
> 
>  drivers/gpu/drm/drm_crtc.c | 50 ++++++++++++++++++++++++++++++++++++++++---
>  drivers/gpu/drm/drm_drv.c  |  6 +++++-
>  include/drm/drm_crtc.h     |  3 ++-
>  3 files changed, 54 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 76453cd..2ad0ce9 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1080,13 +1080,57 @@ void drm_connector_unregister(struct drm_connector
> *connector) }
>  EXPORT_SYMBOL(drm_connector_unregister);
> 
> +/**
> + * drm_connector_register_all - register all connectors
> + * @dev: drm device
> + *
> + * This function just calls drm_connector_register() for all connectors.
> + * Should be called when the device is disconnected, e.g. from an usb
> driver's
> + * ->connect callback.

There's no such thing as a USB driver connect callback :-)

> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + */
> +int drm_connector_register_all(struct drm_device *dev)
> +{
> +	struct drm_connector *connector, *failed;
> +	int ret;
> +
> +	mutex_lock(&dev->mode_config.mutex);
> +
> +	drm_for_each_connector(connector, dev) {
> +		ret = drm_connector_register(connector);
> +		if (ret) {
> +			failed = connector;
> +			goto err;
> +		}
> +	}
> +
> +

One blank line is enough.

> +	mutex_unlock(&dev->mode_config.mutex);
> +
> +	return 0;
> +
> +err:
> +	drm_for_each_connector(connector, dev) {
> +		if (failed == connector)
> +			break;
> +
> +		drm_connector_unregister(connector);
> +	}

drm_connector_unregister() can safely be called on unregistered connectors, so 
you could simplify the implementation by calling 
drm_connector_unregister_all() above and remove the goto and this piece of 
error handling code.

> +	mutex_unlock(&dev->mode_config.mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(drm_connector_register_all);
> 
>  /**
>   * drm_connector_unregister_all - unregister connector userspace interfaces
> * @dev: drm device
>   *
>   * This function unregisters all connector userspace interfaces in sysfs.
> Should
> - * be call when the device is disconnected, e.g. from an usb driver's
> + * be called when the device is disconnected, e.g. from an usb driver's
>   * ->disconnect callback.
>   */
>  void drm_connector_unregister_all(struct drm_device *dev)
> @@ -1094,9 +1138,9 @@ void drm_connector_unregister_all(struct drm_device
> *dev) struct drm_connector *connector;
> 
>  	/* FIXME: taking the mode config mutex ends up in a clash with sysfs */
> -	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
> +	drm_for_each_connector(connector, dev) {
>  		drm_connector_unregister(connector);
> -
> +	}
>  }
>  EXPORT_SYMBOL(drm_connector_unregister_all);

I would move these two hunks to the previous patch as you already touch 
drm_connector_unregister_all() there, but that's up to you.

> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 167c8d3..5580a90 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -715,7 +715,11 @@ EXPORT_SYMBOL(drm_dev_unref);
>   *
>   * Register the DRM device @dev with the system, advertise device to
> user-space * and start normal device operation. @dev must be allocated via
> drm_dev_alloc() - * previously.
> + * previously. Right after drm_dev_register() the driver should call
> + * drm_connector_plug_all() to register all connectors in sysfs. This is

s/drm_connector_plug_all/drm_connector_register_all/

> + * a separate call for backward compatibility with drivers still using
> + * the deprecated ->load() callback, where connectors are registered from
> within
> + * the ->load() callback.
>   *
>   * Never call this twice on any device!
>   *
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 42d9f4d..6a34117 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -2214,7 +2214,8 @@ void drm_connector_unregister(struct drm_connector
> *connector);
> 
>  extern void drm_connector_cleanup(struct drm_connector *connector);
>  extern unsigned int drm_connector_index(struct drm_connector *connector);
> -/* helper to unregister all connectors from sysfs for device */
> +/* helpers to {un}register all connectors from sysfs for device */
> +extern int drm_connector_register_all(struct drm_device *dev);
>  extern void drm_connector_unregister_all(struct drm_device *dev);
> 
>  extern int drm_bridge_add(struct drm_bridge *bridge);

-- 
Regards,

Laurent Pinchart