pwm_bl on i.MX6Q broken on 5.4-RC1+

[Adam Ford]

I have an i.MX6Q with an LCD and PWM controlled backlight.  On 5.4-RC1
through the current master (16 Oct 2019), the backlight does not come
on by default.  I can get it come on by manually setting the
brightness, but any video activity seems to blank the screen again
until I change the brightness again.

I bisected the patch to 01ccf903edd6 ("pwm: Let pwm_get_state() return
the last implemented state")

If I revert this patch on 5.4-rc3, the issue goes away.

I was hoping someone might have a suggestion on how to fix it to play
nicely with the iMX6Q PWM or revert if no solution can be found.

thank you,

adam