FLEXCAN fails to probe (i.mx6sx)

[kubiznak_petr]

I'm having an issue with FLEXCAN on i.mx6sx. It fails to probe during Linux bootup (linux-fslc v4.1-2.0.x).

In dts, I just enable the peripheral:

&flexcan1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_flexcan1_1>;
status = "okay";
};

...

pinctrl_flexcan1_1: flexcan1grp_1 {
fsl,pins = <
MX6SX_PAD_SD3_DATA5__CAN1_TX 0x1b0b0
MX6SX_PAD_SD3_DATA7__CAN1_RX 0x1b0b0
>;
};

Kernel boot log:

CAN device driver interface
2090000.can supply xceiver not found, using dummy regulator
flexcan 2090000.can: registering netdev failed
flexcan: probe of 2090000.can failed with error -110

After debugging the driver, I found register_flexcandev() enables the two clocks and calls flexcan_chip_disable() which timeouts.

I guess I'm missing some stupid little thing here. Does anybody have a suggestion what's wrong?

[kubiznak_petr]

<dummy>

[igorpadykov]

Hi kubiznak_petr

for community linux "linux-fslc" one can look at boundary devices settings in

https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_4.1.15_2.0.0_ga/arch/arm/boot/dts/im...

https://github.com/boundarydevices/u-boot-imx6/tree/boundary-v2016.03/board/boundary/nitrogen6sx

Best regards
igor

[kubiznak_petr]

Hi igor,

Thanks for your reply. I don't see any remarkable difference in the referenced dts file. I neither see anything remarkable in the u-boot - they only configure the pads, that shouldn't play any role, right?

I've cut the dts node to the minimum, i.e.:

&flexcan1 {
status = "okay";
};

Hence only enabling the node as defined in imx6sx.dtsi. Still does not work. The same behaviour for flexcan2.

Any idea why the FLEXCAN_MCR_LPM_ACK flag is not asserted?

Best Regards,
Petr

[kubiznak_petr]

Hi igor,

Thanks for your reply. I don't see any remarkable difference in the referenced dts file. I neither see anything remarkable in the u-boot - they only configure the pads, that shouldn't play any role, right?

I've cut the dts node to the minimum, i.e.:

&flexcan1 {
status = "okay";
};

Hence only enabling the node as defined in imx6sx.dtsi. Still does not work. The same behaviour for flexcan2.

Any idea why the FLEXCAN_MCR_LPM_ACK flag is not asserted?

Best Regards,
Petr

[igorpadykov]

Hi Petr

one can try to debug in probe() function using

AN4553 Using Open Source Debugging Tools for Linux on i.MX Processors
https://www.nxp.com/docs/en/application-note/AN4553.pdf

Best regards
igor