Ci_hdrc ci_hdrc.0: Device No Response Log messages

Hi,

every 15 seconds I get a message in the system log:

ci_hdrc ci_hdrc.0: Device No Response

How can I find out where this comes from? Is it related to USB?

Best regards,
Matthias Kock

Hi @mkock

Could you provide the version of the hardware (including carrier board) of your module?
Have you done any changes to the kernel .config and other system files?
Which devices did you connect to the USB Connector?

Best regards,
Jaski

I was wrong. It is not connected to the number of frequency points, but if the display is on:

echo 1 > /sys/class/backlight/backlight/bl_power

turns the display off (I changed the backlight polarity in DTS).

In this case no more error messages ocurr. We are using a Densitron display, that is connected via RGB. The display is working, how can I find out where the error message comes from?

Best,
Matthias

Hi,
in the meantime I could track it down. Using many brigness-levels for backlight in imx6qdl-apalis-eval.dtsi leads to this error.
Our carrier board is custom design. You will probably be able to reproduce this with the default (legacy) 2.7 ( or even newer) image by just increasing the number of brightness-level points:

&backlight {
#if 1 /* PWM polarity: if 1 is brightest */
	pwms = <&pwm4 0 5000000 0>;
#if 0 /* Fusion 7 needs 10kHz PWM frequency */
	pwms = <&pwm4 0 100000 0>;
#endif
#else /* PWM polarity: if 0 is brightest */
	pwms = <&pwm4 0 5000000 1>;
#endif
	/*brightness-levels = <0 4 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 255>; leads to a system log entry every 15s: "ci_hdrc ci_hdrc.0: Device No Response"  */
	brightness-levels = <0 4 10 20 30 50 60 75 90 100 115 130 140 155 170  190 200  210 220 230 240 255>; /* ok, but less points */
	default-brightness-level = <0>; /*we do not want the kernel to turn on the display*/
	status = "okay";
};

I could not spot anything particular wrong with this. For compatibility reasons with our existing software I would like to keep using exact these points (The brightness settings work, expect that something else might break).
Is it a bug?

Best,
Matthias

Hi @mkock

I don’t the message above is related to backlight or display but more to USB. So you should look in this part.

Best regards,
Jaski