Enric Balletbo i Serra enric.balletbo@collabora.com writes:
Commit '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")' allows the possibility to compute a default brightness table when there isn't the brightness-levels property in the DT. Unfortunately the changes made broke the pwm backlight for the non-DT boards.
Usually, the non-DT boards don't pass the brightness levels via platform data, instead, they set the max_brightness in their platform data and the driver calculates the level without a table. The ofending patch assumed that when there is no brightness levels table we should create one, but this is clearly wrong for the non-DT case.
After this patch the code handles the DT and the non-DT case taking in consideration also if max_brightness is set or not. The default table is only created when neither, brightness-levels and max_brightness, are set.
The patch also fixes another issue found by Robert. Before this patch looks like a division by 0 was possible when state.period returned 0 by pwm_get_state(). This is because pwm_get_state() was called before pwm_apply_args() so state.period was not initialized. The patch moves the pwm_apply_args() call before any call to pwm_get_state().
Fixes: '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")' Reported-by: Robert Jarzmik robert.jarzmik@free.fr Signed-off-by: Enric Balletbo i Serra enric.balletbo@collabora.com
Tested-by: Robert Jarzmik robert.jarzmik@free.fr
Cheers.
-- Robert