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X-CSE-ConnectionGUID: ukI7UraHQZWlBsE41x+nuw== X-CSE-MsgGUID: 9dbC9UkcSjeVY66EWDda/w== X-IronPort-AV: E=McAfee;i="6700,10204,11175"; a="26850981" X-IronPort-AV: E=Sophos;i="6.10,177,1719903600"; d="scan'208";a="26850981" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2024 04:18:15 -0700 X-CSE-ConnectionGUID: +N4DJMNfR8S4MROy934LWA== X-CSE-MsgGUID: P7pm5zNjRpOob5mLhis37A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,177,1719903600"; d="scan'208";a="93209029" Received: from black.fi.intel.com ([10.237.72.28]) by orviesa002.jf.intel.com with ESMTP; 26 Aug 2024 04:18:12 -0700 Received: by black.fi.intel.com (Postfix, from userid 1001) id 0B83053C; Mon, 26 Aug 2024 14:18:11 +0300 (EEST) Date: Mon, 26 Aug 2024 14:18:11 +0300 From: Mika Westerberg To: Oleksandr Ocheretnyi Cc: Wim Van Sebroeck , Guenter Roeck , Jean Delvare , Wolfram Sang , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, xe-linux-external@cisco.com Subject: Re: [PATCH v1] iTCO_wdt: ignore NMI_NOW bit on register comparison Message-ID: <20240826111811.GP1532424@black.fi.intel.com> References: <20240826075303.3964392-1-oocheret@cisco.com> Precedence: bulk X-Mailing-List: linux-watchdog@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240826075303.3964392-1-oocheret@cisco.com> 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 > --- > 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! > newval = inw(TCO1_CNT(p)); > > /* make sure the update is successful */ > -- > 2.39.3