于 2012年07月13日 19:50, Kumar Gala 写道:
On Jul 12, 2012, at 9:44 PM, Jiang Lu wrote:
On PPC44x core, the WRC(Watchdog-timer Reset Control) field of TCR
of timer can not reset by software after set to a non-zero value.
Which means software can not reset the timeout behaviour of watchdog timer.
This patch selects WATCHDOG_NOWAYOUT option for 44x platforms to
indicate the watchdog timer can not be disabled once fired.
Signed-off-by: Jiang Lu <lu.ji...@windriver.com>
---
drivers/watchdog/Kconfig | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
I believe this is not 44x specific, but how Book-E watchdog is architected.
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 3709624..41f3dff 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1084,6 +1084,7 @@ config PIKA_WDT
config BOOKE_WDT
tristate "PowerPC Book-E Watchdog Timer"
depends on BOOKE || 4xx
+ select WATCHDOG_NOWAYOUT if 44x
This should probably be 'select WATCHDOG_NOWAYOUT if BOOKE'
On ppc44x's processor, if we disabled 'WATCHDOG_NOWAYOUT ' option. The
driver's release routine will try to disable the watchdog , by clearing
the WIE & WTDP field in TCR.
Since the ppc44x's watch dog can not reset by software, such operation
only set the timeout value(WDTP) to minimum, and cause the system reboot
immediately.
I checked ppc 476, 405 & 450's manual, these document said the
WRC(Watchdog-timer Reset Control) field of TCR of timer
can not reset by software after set to a non-zero value. I think all
ppc44x core should got same limitation.
While on FSL's platform, we did not met such issue. So I think we should
select 'WATCHDOG_NOWAYOUT' option for 44x platform.
Regards,
Jiang Lu
---help---
Watchdog driver for PowerPC Book-E chips, such as the Freescale
MPC85xx SOCs and the IBM PowerPC 440.
--
1.7.7
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