Re: [PATCH 27/52] drm: Manage drm_mode_config_init with drmm_

On Wed, Feb 19, 2020 at 2:50 PM Laurent Pinchart laurent.pinchart@ideasonboard.com wrote:

Hi Daniel,

Thank you for the patch.

On Wed, Feb 19, 2020 at 11:20:57AM +0100, Daniel Vetter wrote:

...

drm_mode_config_cleanup is idempotent, so no harm in calling this twice. This allows us to gradually switch drivers over by removing explicit drm_mode_config_cleanup calls.

With this step it's not also possible that (at least for simple drivers) automatic resource cleanup can be done correctly without a drm_driver->release hook. Therefore allow this now in devm_drm_dev_init().

Also with drmm_ explicit drm_driver->release hooks are kinda not the best option, so deprecate that hook to discourage future users.

v2: Fixup the example in the kerneldoc too.

Cc: "Noralf Trønnes" noralf@tronnes.org Cc: Sam Ravnborg sam@ravnborg.org Cc: Thomas Zimmermann tzimmermann@suse.de Signed-off-by: Daniel Vetter daniel.vetter@intel.com

---

drivers/gpu/drm/drm_drv.c | 21 +++++---------------- drivers/gpu/drm/drm_mode_config.c | 12 +++++++++++- include/drm/drm_mode_config.h | 2 +- 3 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 3cf40864d4a6..428c569aaaf1 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -267,8 +267,7 @@ void drm_minor_release(struct drm_minor *minor)

• The following example shows a typical structure of a DRM display driver.
• The example focus on the probe() function and the other functions that is

• • almost always present and serves as a demonstration of devm_drm_dev_init()
• • usage with its accompanying drm_driver->release callback.

• • almost always present and serves as a demonstration of devm_drm_dev_init().
  • .. code-block:: c

@@ -278,16 +277,8 @@ void drm_minor_release(struct drm_minor *minor)

•       struct clk *pclk;
  

• };

• • static void driver_drm_release(struct drm_device *drm)
• • {

• •       struct driver_device *priv = container_of(...);
    

• •       drm_mode_config_cleanup(drm);
    

• • }
• • static struct drm_driver driver_drm_driver = {

  •       [...]
    

• •       .release = driver_drm_release,
    

  • };
  • static int driver_probe(struct platform_device *pdev)

@@ -312,7 +303,9 @@ void drm_minor_release(struct drm_minor *minor)

•       }
  

•       drmm_add_final_kfree(drm, priv);
  

• •       drm_mode_config_init(drm);
    

• •       ret = drm_mode_config_init(drm);
    

• •       if (ret)
    

• •               return ret;
    

  •       priv->userspace_facing = drmm_kzalloc(..., GFP_KERNEL);
    

  •       if (!priv->userspace_facing)
    

@@ -710,8 +703,7 @@ static void devm_drm_dev_init_release(void *data)

• @driver: DRM driver
• Managed drm_dev_init(). The DRM device initialized with this function is

• • automatically put on driver detach using drm_dev_put(). You must supply a
• • &drm_driver.release callback to control the finalization explicitly.

• • automatically put on driver detach using drm_dev_put().
  • RETURNS:
  • 0 on success, or error code on failure.

@@ -722,9 +714,6 @@ int devm_drm_dev_init(struct device *parent, { int ret;

• if (WARN_ON(!driver->release))
  

•         return -EINVAL;
  

• ret = drm_dev_init(dev, driver, parent);
  if (ret)
          return ret;
  

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index 08e6eff6a179..957db1edba0c 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -25,6 +25,7 @@ #include <drm/drm_drv.h> #include <drm/drm_encoder.h> #include <drm/drm_file.h> +#include <drm/drm_managed.h> #include <drm/drm_mode_config.h> #include <drm/drm_print.h> #include <linux/dma-resv.h> @@ -373,6 +374,11 @@ static int drm_mode_create_standard_properties(struct drm_device *dev) return 0; }

+static void drm_mode_config_init_release(struct drm_device *dev, void *ptr) +{

• drm_mode_config_cleanup(dev);
  

+}

/**

• drm_mode_config_init - initialize DRM mode_configuration structure
• @dev: DRM device

@@ -384,8 +390,10 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)

• problem, since this should happen single threaded at init time. It is the
• driver's problem to ensure this guarantee.

• • Cleanup is automatically handled through registering drm_mode_config_cleanup
• • with drmm_add_action().
  */

-void drm_mode_config_init(struct drm_device *dev) +int drm_mode_config_init(struct drm_device *dev) { mutex_init(&dev->mode_config.mutex); drm_modeset_lock_init(&dev->mode_config.connection_mutex); @@ -443,6 +451,8 @@ void drm_mode_config_init(struct drm_device *dev) drm_modeset_acquire_fini(&modeset_ctx); dma_resv_fini(&resv); }

• return drmm_add_action(dev, drm_mode_config_init_release, NULL);
  

If this fails, shouldn't drm_mode_config_cleanup() be called here ?

Maybe for ocd reasons, but not for actually cleaning up anything. It's just a bunch of empty lists that drm_mode_config_cleanup will walk and do nothing about. Not sure I should add that ... -Daniel

...

} EXPORT_SYMBOL(drm_mode_config_init);

diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index 3bcbe30339f0..160a3e4b51c3 100644 --- a/include/drm/drm_mode_config.h +++ b/include/drm/drm_mode_config.h @@ -929,7 +929,7 @@ struct drm_mode_config { const struct drm_mode_config_helper_funcs *helper_private; };

-void drm_mode_config_init(struct drm_device *dev); +int drm_mode_config_init(struct drm_device *dev); void drm_mode_config_reset(struct drm_device *dev); void drm_mode_config_cleanup(struct drm_device *dev);

-- Regards,

Laurent Pinchart