On Wed, Feb 19, 2020 at 2:50 PM Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxx>
> > Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > ---
> > 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
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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