On 8/26/24 08:15, Guenter Roeck wrote:
On 8/26/24 08:12, Guenter Roeck wrote:
On 8/26/24 04:18, Mika Westerberg wrote:
Hi,
On Mon, Aug 26, 2024 at 12:53:01AM -0700, Oleksandr Ocheretnyi wrote:
Commit da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake
PCH iTCO") does not ignore NMI_NOW bit on write operation to TCO1_CNT
register what causes unexpected NMIs due to NMI_NOW bit inversion
during regular crashkernel's workflow with following logs:
iTCO_vendor_support: vendor-support=0
iTCO_wdt iTCO_wdt: unable to reset NO_REBOOT flag, device
disabled by hardware/BIOS
This change clears NMI_NOW bit in the TCO1_CNT register to have no
effect on NMI_NOW bit inversion what can cause NMI immediately.
Fixes: da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake PCH iTCO")
Signed-off-by: Oleksandr Ocheretnyi <oocheret@xxxxxxxxx>
---
drivers/watchdog/iTCO_wdt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index 264857d314da..679c115ef7d3 100644
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -224,7 +224,7 @@ static int update_no_reboot_bit_cnt(void *priv, bool set)
val |= BIT(0);
else
val &= ~BIT(0);
- outw(val, TCO1_CNT(p));
+ outw(val & ~BIT(8), TCO1_CNT(p));
I suggest adding some #define for the magical number 8 so that it is
easier for anyone looking at this driver to figure out what it is doing.
Otherwise looks good to me, thanks!
Not really; it appears to be hiding a change in code which is supposed to do
something different (it is supposed to set or clear the no_reboot bit),
with no explanation whatsoever. That warrants a comment in the code.
Also, I would prefer
val = inw(TCO1_CNT(p)) & ~BIT(8);
On top of that, I fail to understand "on register comparison" in the subject.
What register comparison ?
Sorry, one more: The comment will need to explain why clearing bit 8 is needed
here but not for any other writes to TCO1_CNT. Obviously this isn't just "ignore
bit on write" but something more.
Guenter
