[PATCH v4 1/2] watchdog: imx2_wdt: add external reset support via 'ext-reset-output' dt prop
linux at roeck-us.net
Fri Nov 6 14:02:49 PST 2015
On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote:
> On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck <linux at roeck-us.net> wrote:
> > On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote:
> >> From: Tim Harvey <tharvey at gateworks.com>
> >> The IMX6 watchdog supports assertion of a signal (WDOG_B) which
> >> can be pinmux'd to an external pin. This is typically used for boards that
> >> have PMIC's in control of the IMX6 power rails. In fact, failure to use
> >> such an external reset on boards with external PMIC's can result in various
> >> hangs due to the IMX6 not being fully reset  as well as the board failing
> >> to reset because its PMIC has not been reset to provide adequate voltage for
> >> the CPU when coming out of reset at 800Mhz.
> >> This uses a new device-tree property 'ext-reset-output' to indicate the
> >> board has such a reset and to cause the watchdog to be configured to assert
> >> WDOG_B instead of an internal reset both on a watchdog timeout and in
> >> system_restart.
> >>  http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333689.html
> >> Cc: Lucas Stach <l.stach at pengutronix.de>
> >> Signed-off-by: Tim Harvey <tharvey at gateworks.com>
> >> ---
> >> .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 2 ++
> >> drivers/watchdog/imx2_wdt.c | 20 ++++++++++++++++++--
> >> 2 files changed, 20 insertions(+), 2 deletions(-)
> >> diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
> >> index 8dab6fd..9b89b3a 100644
> >> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
> >> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
> >> @@ -9,6 +9,8 @@ Optional property:
> > properties ?
> >> - big-endian: If present the watchdog device's registers are implemented
> >> in big endian mode, otherwise in native mode(same with CPU), for more
> >> detail please see: Documentation/devicetree/bindings/regmap/regmap.txt.
> >> +- ext-reset-output: If present the watchdog device is configured to assert its
> > Should that have a vendor prefix ? Also, not sure if "-output"
> > has any real value in the property name. "fsl,external-reset", maybe ?
> Hi Guenter,
> I don't see why a vendor prefix is necessary - its a feature of the
> IMX6 watchdog supported by this driver to be able to trigger an
> internal chip-level reset and/or an external signal that can be hooked
> to additional hardware.
Sounded like vendor specific to me, but then I am not a devicetree maintainer,
so I am not an authority on the subject.
> I started with ext-reset, but it was suggested
> to also make it clear that this is an 'output' and not a reset input.
No problem, as long as you get an Ack from a devicetree maintainer.
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