Re: [PATCH 4/5] drm: Allow const struct drm_driver

[Alex Deucher <alexdeucher@gmail.com>]

On Fri, Oct 30, 2020 at 6:11 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> It's nice if a big function/ioctl table like this is const. Only
> downside here is that we need a few more #ifdef to paper over the
> differences when CONFIG_DRM_LEGACY is enabled. Maybe provides more
> motivation to sunset that horror show :-)
>
> v2:
> - Fix super important checkpatch warning (Sam)
> - Update the kerneldoc example too (Sam)
>
> Acked-by: Maxime Ripard <mripard@kernel.org>
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

> ---
>  drivers/gpu/drm/drm_drv.c | 17 +++++++++++------
>  include/drm/drm_device.h  |  4 ++++
>  include/drm/drm_drv.h     |  5 +++--
>  3 files changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 457ac0f82be2..0371d1f095b2 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -284,7 +284,7 @@ void drm_minor_release(struct drm_minor *minor)
>   *             struct clk *pclk;
>   *     };
>   *
> - *     static struct drm_driver driver_drm_driver = {
> + *     static const struct drm_driver driver_drm_driver = {
>   *             [...]
>   *     };
>   *
> @@ -574,7 +574,7 @@ static void drm_dev_init_release(struct drm_device *dev, void *res)
>  }
>
>  static int drm_dev_init(struct drm_device *dev,
> -                       struct drm_driver *driver,
> +                       const struct drm_driver *driver,
>                         struct device *parent)
>  {
>         int ret;
> @@ -589,7 +589,11 @@ static int drm_dev_init(struct drm_device *dev,
>
>         kref_init(&dev->ref);
>         dev->dev = get_device(parent);
> +#ifdef CONFIG_DRM_LEGACY
> +       dev->driver = (struct drm_driver *)driver;
> +#else
>         dev->driver = driver;
> +#endif
>
>         INIT_LIST_HEAD(&dev->managed.resources);
>         spin_lock_init(&dev->managed.lock);
> @@ -663,7 +667,7 @@ static void devm_drm_dev_init_release(void *data)
>
>  static int devm_drm_dev_init(struct device *parent,
>                              struct drm_device *dev,
> -                            struct drm_driver *driver)
> +                            const struct drm_driver *driver)
>  {
>         int ret;
>
> @@ -678,7 +682,8 @@ static int devm_drm_dev_init(struct device *parent,
>         return ret;
>  }
>
> -void *__devm_drm_dev_alloc(struct device *parent, struct drm_driver *driver,
> +void *__devm_drm_dev_alloc(struct device *parent,
> +                          const struct drm_driver *driver,
>                            size_t size, size_t offset)
>  {
>         void *container;
> @@ -713,7 +718,7 @@ EXPORT_SYMBOL(__devm_drm_dev_alloc);
>   * RETURNS:
>   * Pointer to new DRM device, or ERR_PTR on failure.
>   */
> -struct drm_device *drm_dev_alloc(struct drm_driver *driver,
> +struct drm_device *drm_dev_alloc(const struct drm_driver *driver,
>                                  struct device *parent)
>  {
>         struct drm_device *dev;
> @@ -858,7 +863,7 @@ static void remove_compat_control_link(struct drm_device *dev)
>   */
>  int drm_dev_register(struct drm_device *dev, unsigned long flags)
>  {
> -       struct drm_driver *driver = dev->driver;
> +       const struct drm_driver *driver = dev->driver;
>         int ret;
>
>         if (!driver->load)
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index f4f68e7a9149..2c361964aee7 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -83,7 +83,11 @@ struct drm_device {
>         } managed;
>
>         /** @driver: DRM driver managing the device */
> +#ifdef CONFIG_DRM_LEGACY
>         struct drm_driver *driver;
> +#else
> +       const struct drm_driver *driver;
> +#endif
>
>         /**
>          * @dev_private:
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 7af220226a25..cc9da43b6eda 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -516,7 +516,8 @@ struct drm_driver {
>  #endif
>  };
>
> -void *__devm_drm_dev_alloc(struct device *parent, struct drm_driver *driver,
> +void *__devm_drm_dev_alloc(struct device *parent,
> +                          const struct drm_driver *driver,
>                            size_t size, size_t offset);
>
>  /**
> @@ -549,7 +550,7 @@ void *__devm_drm_dev_alloc(struct device *parent, struct drm_driver *driver,
>         ((type *) __devm_drm_dev_alloc(parent, driver, sizeof(type), \
>                                        offsetof(type, member)))
>
> -struct drm_device *drm_dev_alloc(struct drm_driver *driver,
> +struct drm_device *drm_dev_alloc(const struct drm_driver *driver,
>                                  struct device *parent);
>  int drm_dev_register(struct drm_device *dev, unsigned long flags);
>  void drm_dev_unregister(struct drm_device *dev);
> --
> 2.28.0
>
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