On Wed, Oct 18, 2017 at 02:28:10PM +0000, Steve Twiss wrote: > Hi Michael, > > On 17 October 2017 16:30 Michael Grzeschik wrote: > > > To: linux-watchdog@xxxxxxxxxxxxxxx > > Subject: [PATCH 3/6] watchdog: da9062: reset board on watchdog timeout > > > > From: Stefan Christ <s.christ@xxxxxxxxx> > > > > In the default fuse configuration the watchdog poweroffs the system > > instead of resetting it on a watchdog timeout. This patch changes the > > behavior. Now the board is reseted and reboots. > > We call the chip's fuze configuration the "OTP" (one-time programming). > > > > > Note: This patch requires that the config register CONFIG_I is > > configured as writable in the da9062 multi function device. > > > > Signed-off-by: Stefan Christ <s.christ@xxxxxxxxx> > > Signed-off-by: Christian Hemp <c.hemp@xxxxxxxxx> > > --- > > drivers/watchdog/da9062_wdt.c | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/drivers/watchdog/da9062_wdt.c > > b/drivers/watchdog/da9062_wdt.c > > index 4349a02215489..b95719b349e5c 100644 > > --- a/drivers/watchdog/da9062_wdt.c > > +++ b/drivers/watchdog/da9062_wdt.c > > @@ -112,6 +112,20 @@ static int da9062_wdt_start(struct watchdog_device > > *wdd) > > unsigned int selector; > > int ret; > > > > + /* > > + * Use da9062's SHUTDOWN mode instead of POWERDOWN for watchdog reset. > > + * On timeout the PMIC should reset the system, not powering it > > + * off. > > + */ > > + ret = regmap_update_bits(wdt->hw->regmap, > > + DA9062AA_CONFIG_I, > > + DA9062AA_WATCHDOG_SD_MASK, > > + DA9062AA_WATCHDOG_SD_MASK); > > + if (ret) > > + dev_err(wdt->hw->dev, > > + "failed to set wdt reset mode. Expect poweroff on watchdog reset: %d\n", > > + ret); > > + > > I am not quite understanding what you are trying to achieve. > It seems there could be be few different options here. > > If the watchdog is running from power on and if the platform hangs early in the start-up > sequence, then waiting to set WATCHDOG_SD in the DA9062 watchdog driver could be > too late to modify the chip's behaviour. If the watchdog tripped early, the system might > already be in POWERDOWN instead of SHUTDOWN before this point. Agreed. > If a software change to CONFIG_I is to be done, then this register could be modified very > early in the bootloader. If necessary, the Linux kernel driver can read the CONFIG_I register > and decide if it needs to modify its behaviour accordingly. In this case, write changes to > CONFIG_I would not be needed. I will add that condition around it. > The trivial option (for software at least) could be a different OTP: to enforce > WATCHDOG_SD in the hardware. That is one god point. I will have a look into that. > DA9062 Datasheet revision 3.4, 27-Jun-2017, page 59, Section 10. > A hyperlink to the latest datasheet can be found in the DA9062 binding file: > Documentation/devicetree/bindings/mfd/da9062.txt On Page 59 of this document are only ordering informations. > It doesn't seem correct to make this a permanent change in the general Linux kernel driver. > At the very least, something like this sould be protected by a device tree boolean. Agreed. I will think adopt your ideas. Regards, Michael -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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