Hello,
I want to port the unblank_delay=200 setting of "i.MX6 Linux Release B2020.04 (Buildroot)". Meanwhile i switched to using the panel-lvds devicenode. How can this be done?
Thank you in advance.
Greetings,
André Wagner
PS: What did this setting exactly on the physical level with the regulator and pwm of the backlight and the display itself? I found something already affecting this in drivers/video/backlight/pwm_bl.c
Hello,
unblank_delay basically delayed the enable of the backlight by introducing a msleep at the end of the ipu init function.
https://github.com/FSEmbedded/…7dc798b5c3909c73a30e8f02f
You should get a similar functionality by adding the value post-pwm-on-delay-ms to your pwm-backlight node.
https://github.com/FSEmbedded/…klight/pwm-backlight.yaml
Your F&S Support Team
Thanks for your answer.
Meanwhile i found exactly the same and i tried i by setting post-pwm-on-delay-ms but i got still a white flashing while boot up. I would say it even get slightly longer...
Did you try a really long time span like 2000ms?
Just to make sure if its an timing issue or a driver sequence issue.
Your F&S Support Team
Also, could you post a snippet of your lvds-panel and backlight device tree nodes?
Yes of cause, here the decompiled devicetree where I set the delay to 20s:
backlight_ldb {
compatible = "regulator-fixed";
regulator-name = "ldb-bl";
gpio = <0x12 0x08 0x00>;
regulator-min-microvolt = <0x325aa0>;
regulator-max-microvolt = <0x325aa0>;
enable-active-high;
phandle = <0x6f>;
};
backlight_ldb {
compatible = "pwm-backlight";
power-supply = <0x6f>;
post-pwm-on-delay-ms = <0x4e20>;
pwms = <0x70 0x00 0x4c4b40 0x00>;
brightness-levels = <0x00 0x01 0x05 0x0a 0x12 0x1c 0x29 0x38 0x49 0x5c 0x71 0x89 0xa3 0xc0 0xde 0xff>;
default-brightness-level = <0x0e>;
fb-names = "ldb0\0ldb1";
phandle = <0x73>;
};
panel-lvds0 {
compatible = "panel-lvds";
data-mapping = "vesa-24";
width-mm = <0x9a>;
height-mm = <0x56>;
backlight = <0x73>;
power-supply = <0x03>;
panel-timing {
clock-frequency = <0x25f4cc0>;
hactive = <0x320>;
vactive = <0x258>;
hback-porch = <0x58>;
hfront-porch = <0x28>;
hsync-len = <0x80>;
vback-porch = <0x14>;
vfront-porch = <0x06>;
vsync-len = <0x02>;
hsync-active = <0x00>;
vsync-active = <0x00>;
de-active = <0x01>;
pixelclk-active = <0x00>;
};
port {
endpoint {
remote-endpoint = <0x74>;
phandle = <0x07>;
};
};
};
With setting the delay to 20s I see first the white flicker and then black for 20s. I looked in the pwm-backlight code in pwm_bl.c. When I understood right the delay is setting the gpio defined in its devicetree node property enable-gpio (which is not set in the armstone devicetree at all) after the delay set in node property post-pwm-on-delay-ms.
Is it perhaps a solution to move the gpio node of regulator fixed to pwm-backlight enable-gpio?
So switching from gpio->regulator->backlight to gpio->backlight?
Greetings,
André Wagner
Yes this is true.
The driver first enables the regulator then does the sleep and finally enables the enable-gpio.
https://github.com/FSEmbedded/…eo/backlight/pwm_bl.c#L57
You could try to add the property enable-gpio to the backlight node using the gpio from the backlight regulator.
Your F&S Support Team
Moving the gpio from the regulator to the pwm-backlight node did the trick. Now there is no white flashing anymore.
Thank you very much for your support!
