Dear Alexander Stein,
In message 1280145784-18909-1-git-send-email-alexander.stein@systec-electronic.com you wrote:
On AT91 the watchdog mode register can only be written once after reset. If this register is written by u-boot e.g. a Linux driver can't reconfigure the watchdog later. If the watchdog is left untouched this is possible. Without touching the mode register the watchdog has a default setup and u-boot is still able to trigger the watchdog.
Signed-off-by: Alexander Stein alexander.stein@systec-electronic.com
Changes in v2:
- Add a new specific option CONFIG_SKIP_WATCHDOG_INIT
- Add some documentation
Changes in v3:
- Be more verbose in describing the problem in the commit message and README
README | 11 +++++++++++ arch/arm/cpu/arm926ejs/at91/lowlevel_init.S | 2 ++ 2 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/README b/README index a9c98f2..110668d 100644 --- a/README +++ b/README @@ -2817,6 +2817,17 @@ Low Level (hardware related) configuration options: some other boot loader or by a debugger which performs these initializations itself.
+- CONFIG_SKIP_WATCHDOG_INIT
[arm AT91 only] If this variable is defined, then thewatchdog will not be programmed upon u-boot start.On AT91 the watchdog mode register can only be writtenonce after reset. If this register is written by u-boote.g. a Linux driver can't reconfigure the watchdog later. Ifthe watchdog is left untouched this is possible.Without touching the mode register the watchdog has a defaultsetup and u-boot is still able to trigger the watchdog.
I think the Subject: is wrong. It reads:
Don't initialize watchdog if CONFIG_SKIP_WATCHDOG_INIT is undefined
I think you mean "if CONFIG_SKIP_WATCHDOG_INIT is _DEFINED_" ?
Best regards,
Wolfgang Denk