From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail1.windriver.com (mail1.windriver.com [147.11.146.13]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mail1.windriver.com", Issuer "Intel External Basic Issuing CA 3A" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 18E642C00DD for ; Mon, 16 Jul 2012 12:07:38 +1000 (EST) Message-ID: <50037762.4000800@windriver.com> Date: Mon, 16 Jul 2012 10:07:30 +0800 From: "Lu.Jiang" MIME-Version: 1.0 To: Kumar Gala Subject: Re: [PATCH] ppc44x/watchdog: Select WATCHDOG_NOWAYOUT option References: <1342147473-20231-1-git-send-email-lu.jiang@windriver.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Cc: linuxppc-dev@lists.ozlabs.org Reply-To: lu.jiang@windriver.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 >> --- >> 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 >> >> _______________________________________________ >> Linuxppc-dev mailing list >> Linuxppc-dev@lists.ozlabs.org >> https://lists.ozlabs.org/listinfo/linuxppc-dev >