On Mon, Aug 9, 2010 at 2:40 AM, Alexander Stein 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
Changes in v4:
- Fix commit message
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 b6bf451..9fbb6c9 100644 --- a/README +++ b/README @@ -2827,6 +2827,17 @@ 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 the
- watchdog will not be programmed upon u-boot start.
- 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.
isnt the at91 logic inverted ? shouldnt the watchdog programming only be done when someone has opted in to it via some watchdog define ? -mike