On 04/12/2019 09.45, Marc Kleine-Budde wrote:
On 12/4/19 3:22 AM, Joakim Zhang wrote:
-----Original Message-----
From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Sent: 2019年12月4日 2:15
To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; sean@xxxxxxxxxx;
linux-can@xxxxxxxxxxxxxxx
Cc: dl-linux-imx <linux-imx@xxxxxxx>; netdev@xxxxxxxxxxxxxxx
Subject: Re: [PATCH V2 2/4] can: flexcan: try to exit stop mode during probe
stage
On 11/27/19 6:56 AM, Joakim Zhang wrote:
CAN controller could be stucked in stop mode once it enters stop mode
^^^^^^^ stuck
when suspend, and then it fails to exit stop mode when resume.
How can this happen?
I am also confused how can this happen, as I asked Sean, only CAN
enter stop mode when suspend, then system hang,
How do you recover the system when suspended?
it could let CAN
stuck in stop mode. However, Sean said this indeed happen at his
side, @sean@xxxxxxxxxx, could you explain how this happen in
details?
That would be good.
Only code reset can get CAN out of stop mode,
What is "code reset"?
As I know, "code reset" is to press the POWER KEY from the board. At
my side, reboot command from OS also can get CAN out of stop mode.
Do you mean "cold reset", also known as Power-On-Reset, POR or power cycle?
What does pressing the POWER KEY do? A power cycle of the system or
toggling the reset line of the imx?
We need to describe in detail, as not everyone has the same board as
you, and these boards might not even have a power key :)
Below is experiment I did:
Firstly, do a hacking to let CAN stuck into stop mode, then:
You mean you put the CAN into stop mode without keeping track in the CAN
driver that the CAN-IP is in stop mode, e.g. by hacking the driver.
Then you try several methods to recover:
(1) press power on/off key, get CAN out of stop mode;
(2) reboot command from console, get CAN out of stop mode;
(3) unbind/bind driver, cannot get CAN out of stop mode;
(4) remod/insmod module, cannot get CAN out of stop mode;
(2) resets the complete imx, including the CAN-IP core, (1) probably, too.
No, if the CAN-IP core is in stop-mode it will stay that way even after
a reboot from the console.
At least it's what we are seeing in the field.
This could be because we are missing a wire from the watchdog out to the
RESETBMCU/PWRON on the PMIC.
But i guess a check for if the CAN-Ip is in stop-mode doesn't hurt
anything :)
/Sean
