[U-Boot] u-boot-imx: watchdog driver always asserts WDOG1_B?

[Ross Parker]

I've been hardening up hardware watchdog support on our custom i.MX6q based
boards and think I have found a bug in the U-Boot imx watchdog driver
(imx_watchdog.c).

Currently in the function hw_watchdog_init(), the watchdog control register
bits are explicitly initialised as follows:

writew(WCR_WDZST | WCR_WDBG | WCR_WDE | WCR_WDT | WCR_SRS |
SET_WCR_WT(timeout), &wdog->wcr);

Bit WCR_WDA (bit 5; 0x20) is not mentioned and is therefore set to zero.

The function of that bit is:

"WDA: WDOG_B assertion. Controls the software assertion of the WDOG_B
signal.
0 = Assert WDOG_B output.
1 = No effect on system (Default)."

[Ref. i.MX 6Dual/6Quad Applications Processor Reference Manual, Rev. 3,
07/2015, p5791].

Furthermore:

"70.5.6.2 WDOG_B generation
The WDOG asserts WDOG_B in the following scenarios:
- Software write to WDA bit of Watchdog Control Register (WDOG_WCR).
WDOG_B signal remains asserted as long as the WDA bit is '0'.
..."

[Ref. i.MX 6Dual/6Quad Applications Processor Reference Manual, Rev. 3,
07/2015, p5785]

Sure enough, on my board I'm seeing WDOG1_B being permanently asserted as
soon as that line is executed.

I think that line should be:

writew(WCR_WDZST | WCR_WDBG | WCR_WDE | WCR_WDT | WCR_SRS |
*WCR_WDA |* SET_WCR_WT(timeout), &wdog->wcr);

(And obviously WCR_WDA needs to be defined in "include/fsl_wdog.h".)

Once I made that change, WDOG1_B is no longer asserted when that line is
run and behaves as I expect - i.e. WDOG1_B is asserted when the watchdog
actually fires.

Do others agree - am I on the right track?

If so, should I submit a patch? (Something I have never done before and
should learn how to do...)

Regards,
Ross Parker.