On Thursday, April 29, 2021 1:00 PM, Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote: > On Fri, Apr 23, 2021 at 01:04:23PM +0000, pgeiem wrote: > > > Dear all, > > On a custom board I have a simple DPI panel. Panel's backlight is > > drive with an I2C led driver (PCA9632). led-backlight driver is sued > > to manage this as a backlight. > > When using brightness-levels and default-brightness-level the > > backlight stay turned-off even if manually trying to set a different > > index value to brightness through sysfs. > > I traced this issue as follow: When led_bl_update_status() is called > > the brightness value is returned from backlight_get_brightness() which > > call backlight_is_blank(). In my case backlight_is_blank() return true > > due to props.power = FB_BLANK_POWERDOWN which is != FB_BLANK_UNBLANK. > > I traced why at startup props.power is FB_BLANK_POWERDOWN and found > > that in led_bl_probe() when a default brightness is set (>0) > > props.power is set to FB_BLANK_POWERDOWN which seems incorrect to me. > > I made the small change below and default brightness is correctly used > > at startup. I am not really sure this is an issue and if my change is > > correct or if I am doing something incorrect somewhere else. So I > > first would like to get your opinion on this and if correct will send > > a patch. > > Makes sense. Please send this as a patch. > > Daniel. I finally believe this was correct. A link between the panel and the backlight was missing in dts. With this link the backlight is turned on (props.power = FB_BLANK_UNBLANK) from drm_panel_enable function after enabling the panel. Let me know if you disagree and still believe I should send the patch. Patrick _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
