[PATCH v2 0/24] backlight: add init macros and accessors

[Linus Walleij]

On Sun, Aug 23, 2020 at 12:45 PM Sam Ravnborg <sam at ravnborg.org> wrote:

> The first patch trims backlight_update_status() so it can be called with a NULL
> backlight_device. Then the caller do not need to add this check just to avoid
> a NULL reference.
>
> The backlight drivers uses several different patterns when registering
> a backlight:
>
> - Register backlight and assign properties later
> - Define a local backlight_properties variable and use memset
> - Define a const backlight_properties and assign relevant properties
>
> On top of this there was differences in what members was assigned.
>
> To align how backlight drivers are initialized introduce following helper macros:
> - DECLARE_BACKLIGHT_INIT_FIRMWARE()
> - DECLARE_BACKLIGHT_INIT_PLATFORM()
> - DECLARE_BACKLIGHT_INIT_RAW()
>
> The macros are introduced in patch 2.
>
> The backlight drivers used direct access to backlight_properties.
> Encapsulate these in get/set access operations resulting in following benefits:
> - The access methods can be called with a NULL pointer so logic around the
>   access can be made simpler.
> - The update_brightness and enable_brightness simplifies the users
> - The code is in most cases more readable with the access operations.
> - When everyone uses the access methods refactoring in the backlight core is simpler.
>
> The get/set operations are introduced in patch 3.
>
> The gpio backlight driver received a small overhaul in a set of three patches.
> The result is a smaller and more readable driver.
>
> The remaining patches updates all backlight users in drivers/gpu/drm/*
> With this patch set all of drivers/gpu/drm/:
> - All backlight references to FB_BLANK* are gone from drm/*
> - All direct references to backlight properties are gone
> - All panel drivers uses the devm_ variant for registering backlight
>   Daniel Vetter had some concerns with this for future updates,
>   but we are aligned now and can update if refoctoring demands it
> - All panel drivers uses the backlight support in drm_panel
>
> Individual patches are only sent to the people listed in the patch + a few more.
> Please check https://lore.kernel.org/dri-devel/ for the full series.
>
> v2:
>   - Documented BACKLIGHT_PROPS as it may be used by drivers
>   - Dropped backlight_set_power_{on,off}, they were a mistake (Daniel)
>   - Added backlight_update_brightness() and use it (Daniel)
>   - Added backlight_enable_brightness() and use it
>   - Moved remaining drm_panel driver to use backlight support in drm_panel
>   - gpio backlight driver overhaul
>
> The patches are made on top of the for-backlight-next branch at
> https://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight.git
> The branch needs v5.8-rc1 backported to build as dev_err_probe()
> is used.
>
> The first 6 patches are candidates for the backlight tree.
> If they are applied then this should preferably be to an immutable
> branch we can merge to drm-misc-next where the drm patches shall go.
>
> The drm patches has known conflics and shall *not* be applied to the
> backlight tree, they are included in this patchset to show how the
> new functions are used.
>
> Diffstat for the drm bits alone looks nice:
>  25 files changed, 243 insertions(+), 460 deletions(-)
>
> Feedback welcome!

Thank you for trying to make backlight easier for developers.
I am a big supporter of this type of simplifications and
generalizations, it is what makes DRM great.

The series:
Acked-by: Linus Walleij <linus.walleij at linaro.org>

Yours,
Linus Walleij