i.MX Processors中的主题 Re: i.MX35 FlexCAN 1Mbps Linux problem

i.MX35 FlexCAN 1Mbps Linux problem

z0oba — Mon, 02 Sep 2013 07:17:24 GMT

Hello!

I have a custom board with imx35 processor. Linux kernel is 2.6.31. I need to run CAN on 1 Mbps (on 500 Kbps work fine).

Configure bitrate:

echo 1000000 > /sys/devices/platform/FlexCAN.1/bitrate

The bitrate 1000000 can't supported with clock rate of 66500000

Ok, then i want to choose the other clock source, 24576000Hz as described in the datasheet:

echo osc > /sys/devices/platform/FlexCAN.1/br_clksrc

Then:

ifconfig can1 up

flexcan software Reset Timeouted

ifconfig: SIOCSIFFLAGS: No such device

It` s mean that SOFT_RST bit in MCR doesn`t want to be cleaned.

Have any ideas on this?

Thanks.

Re: i.MX35 FlexCAN 1Mbps Linux problem

gusarambula — Thu, 12 Sep 2013 17:05:56 GMT

It is recommended to change the clock source bit only when the module is in disable mode. I would recommend changing the source code at the flexcan driver’s header file so the driver is loaded with the updated information.

On the flexCAn driver at Linux directory /rpm/BUILD/linux/drivers/net/can/flexcan

You will see the CTRL_CLK_SRC parameter in flexcan.h :

#define __CTRL_CLK_SRC (0x1 << 13)

Change it to (0x0 << 13)

Let me know if this helps.

Re: i.MX35 FlexCAN 1Mbps Linux problem

z0oba — Fri, 13 Sep 2013 10:34:52 GMT

Thanks for your reply!

But changing the source code " #define __CTRL_CLK_SRC (0x0 << 13)" is not helpful.

flexcan software Reset Timeouted

I have used for bit time calculation CAN Bit Time Calculation. And there are not correct parameters for 1Mbs, if we use 66.5Mhz or 24576000Hz clock source.

Maybe, i can change other clock? I can see only these clock sources in the datasheet.