Re: [PATCH v1] iTCO_wdt: ignore NMI_NOW bit on register comparison

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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 ?

Guenter





[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux