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Date: Fri, 8 Oct 2021 09:52:20 +0200 From: Jan Kiszka <jan.kiszka@...mens.com> To: Guenter Roeck <linux@...ck-us.net>, Wim Van Sebroeck <wim@...ux-watchdog.org> Cc: linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org, Mantas Mikulėnas <grawity@...il.com>, "Javier S . Pedro" <debbugs@...ispedro.com> Subject: Re: [PATCH] Revert "watchdog: iTCO_wdt: Account for rebooting on second timeout" On 08.10.21 02:33, Guenter Roeck wrote: > This reverts commit cb011044e34c ("watchdog: iTCO_wdt: Account for > rebooting on second timeout") and commit aec42642d91f ("watchdog: iTCO_wdt: > Fix detection of SMI-off case") since those patches cause a regression > on certain boards (https://bugzilla.kernel.org/show_bug.cgi?id=213809). > > While this revert may result in some boards to only reset after twice > the configured timeout value, that is still better than a watchdog reset > after half the configured value. > > Fixes: cb011044e34c ("watchdog: iTCO_wdt: Account for rebooting on second timeout") > Fixes: aec42642d91f ("watchdog: iTCO_wdt: Fix detection of SMI-off case") > Cc: Jan Kiszka <jan.kiszka@...mens.com> > Cc: Mantas Mikulėnas <grawity@...il.com> > Reported-by: Javier S. Pedro <debbugs@...ispedro.com> > Signed-off-by: Guenter Roeck <linux@...ck-us.net> > --- > drivers/watchdog/iTCO_wdt.c | 12 +++--------- > 1 file changed, 3 insertions(+), 9 deletions(-) > > diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c > index 643c6c2d0b72..ced2fc0deb8c 100644 > --- a/drivers/watchdog/iTCO_wdt.c > +++ b/drivers/watchdog/iTCO_wdt.c > @@ -71,8 +71,6 @@ > #define TCOBASE(p) ((p)->tco_res->start) > /* SMI Control and Enable Register */ > #define SMI_EN(p) ((p)->smi_res->start) > -#define TCO_EN (1 << 13) > -#define GBL_SMI_EN (1 << 0) > > #define TCO_RLD(p) (TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */ > #define TCOv1_TMR(p) (TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/ > @@ -357,12 +355,8 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t) > > tmrval = seconds_to_ticks(p, t); > > - /* > - * If TCO SMIs are off, the timer counts down twice before rebooting. > - * Otherwise, the BIOS generally reboots when the SMI triggers. > - */ > - if (p->smi_res && > - (inl(SMI_EN(p)) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN)) > + /* For TCO v1 the timer counts down twice before rebooting */ > + if (p->iTCO_version == 1) > tmrval /= 2; > > /* from the specs: */ > @@ -527,7 +521,7 @@ static int iTCO_wdt_probe(struct platform_device *pdev) > * Disables TCO logic generating an SMI# > */ > val32 = inl(SMI_EN(p)); > - val32 &= ~TCO_EN; /* Turn off SMI clearing watchdog */ > + val32 &= 0xffffdfff; /* Turn off SMI clearing watchdog */ > outl(val32, SMI_EN(p)); > } > > Sigh, how broken is this architecture of the iTCO? Agreed, this leaves no option then. BTW, the fact that we saw an inconsistency in read-back timeout indicates that there is still an issue for the remaining /= 2 case (means v1), but I'm loosing interest in fixing those issues, given how hard it is to test broadly without breaking users first. Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux
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