treewide: remove references to CREDITS ...

The CREDITS file was removed from barebox in 2015 by commit 6570288f2d97
("Remove the CREDITS file"). Remove references to it from several files.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: backlight-pwm: remove duplicate assignment to object ...

pwm_backlight->period is assigned pwm_get_period(pwm), which is the same
value just a few lines earlier. Remove the superfluous reassignment.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: backlight: add slew time parameter ...

Currently the backlight implementation stretches a brightness change over
a period of 100ms. While this is a fine default for PWM backlights, a user
might wish to change this slew time to meet other constraints or even
completely disable it for some backlight devices.

Add a parameter and provide the default value from the backlight device.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

remove checks for xzalloc() returning NULL ...

xzalloc() either returns memory or panics, so checking for NULL is useless.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: backlight: fix the value of 'brightness_max' ...

Fixes: 87c6a88 video/backlight-pwm: fix the value of 'brightness_max'.

brightness_max should really contain the number of brightness steps, so
the number of elements in the brightness array.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video/backlight-pwm: properly handle the case of an empty 'brightness-levels' in the device tree. ...

In case of an empty 'brightness-levels' array in the device tree or
a non empty one but containing only zeros the value of
'pwm_backlight->scale' would remain 0 possibly causing a division by zero
in the function compute_duty_cycle().

To fix it we check the computed value in case we actually have a 'brightness-levels'
array in the device tree otherwise we implicitly assume a simple array
of the form { 0, 1, 2, ..., 100 } and set the scale to 100.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video/backlight-pwm: code readability improvement. ...

We use the local variable 'length' instead of the lengthy
'pwm_backlight->backlight.brightness_max' within pwm_backlight_parse_dt().

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video/backlight-pwm: fix the value of 'brightness_max'. ...

The field pwm_backlight->backlight.brightness_max should be the maximum
allowed brightness value for the backlight, not the max index of the
array 'pwm_backlight->levels[]'.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video/backlight-pwm: fixed a loop index going out of range. ...

In the function pwm_backlight_parse_dt() the last iteration of the for
loop accessed memory past the end of the array 'pwm_backlight->levels[]'
because of a wrong test ( '<=' instead of '<').

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: pwm-backlight: Honour discrete brightness levels from dt ...

If probed from device tree we have an array of pwm duty cycle levels
in the brightness-levels property. Although the driver parsed the property,
the values have been ignored. Make use of these flags so that the driver
can work for example with inverted PWMs.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: backlight-pwm: Add regulator support ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: backlight-pwm: Add error message ...

Inform the user when we can't find a pwm for the backlight driver.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

video: Add PWM backlight support ...

This adds a backlight driver for backlights controlled by a PWM.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>