On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat <akshay.bhat@xxxxxxxxxxx> wrote: > > > On 11/06/2015 05:02 PM, Guenter Roeck wrote: >> >> 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@xxxxxxxxxxxx> wrote: >>>> >>>> On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote: >>>>> >>>>> From: Tim Harvey <tharvey@xxxxxxxxxxxxx> >>>>> >>>>> 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 [1] 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. >>>>> >>>>> [1] >>>>> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333689.html >>>>> >>>>> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx> >>>>> Signed-off-by: Tim Harvey <tharvey@xxxxxxxxxxxxx> >>>>> --- >>>>> .../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. > > > Devicetree maintainers, > > Any thoughts? > > Tim, > > After looking at all the other watchdog drivers, it does not appear that > there is any other processor which uses a similar feature. Since imx is the > only processor that appears to support this feature, it might make sense in > making this vendor specific. If in the future it is found more processors > support a similar functionality, it can be revisited and moved out from > being vendor specific? > I'm certainly no expert on device-tree policy. I understand your point, but realize that the driver in question is imx2_wdt.c (compatible = "fsl,imx21-wdt"). This is an IP block inside the silicon of only Freescale chips, so its not like a future omap chip would be using this driver - only fsl devices. So why would it need a 'vendor' property any more than its other properties? Regards, Tim -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
