‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Thursday, April 29, 2021 2:07 PM, Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote: > On Thu, Apr 29, 2021 at 11:31:20AM +0000, pgeiem wrote: > > > 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. > > The original logic is definitely wrong. > > However that doesn't mean the driver will be fully correct after fixing > since it does look like is missing the logic found in other similar > drivers (pwm-bl.c and gpio_backlight.c) to handle the various different > cases w.r.t. handover from active backlight by the bootloader. > > Daniel. ok you are right, will see if I can port the logic from others backlight drivers to this one. Patrick _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
