backlight: ktd253: Switch to use dev_err_probe() helper

In the probe path, dev_err() can be replaced with dev_err_probe()
which will check if error code is -EPROBE_DEFER and prints the
error name. It also sets the defer probe reason which can be
checked later through debugfs. It's more simple in error path.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220926142059.2294282-1-yangyingliang@huawei.com

backlight: ktd253: Stabilize backlight

Remove interrupt disablement during backlight setting. It is
way to dangerous and makes platforms instable by having it
miss vblank IRQs leading to the graphics derailing.

The code is using ndelay() which is not available on
platforms such as ARM and will result in 32 * udelay(1)
which is substantial.

Add some code to detect if an interrupt occurs during the
tight loop and in that case just redo it from the top.

Fixes: 5317f37e48b9 ("backlight: Add Kinetic KTD253 backlight driver")
Cc: Stephan Gerhold <stephan@gerhold.net>
Reported-by: newbyte@disroot.org
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

backlight: ktd253: Support KTD259

The KTD259 works just like KTD253 so add this compatible
to the driver.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

backlight: ktd253: Bring up in a known state

The KTD253 backlight might already be on when the driver
is probed: then we don't really know what the current
ratio is and all light intensity settings will be off
relative to what it was at boot.

To fix this, bring up the backlight OFF then move it to
the default backlight from there so we know the state.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

backlight: Add Kinetic KTD253 backlight driver

The Kinetic KTD253 backlight driver is controlled with a
single GPIO line, but still supports a range of brightness
settings by sending fast pulses on the line.

This is based off the source code release for the Samsung
GT-S7710 mobile phone.

Cc: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>