Hi Tim, > On Wed, Dec 2, 2015 at 12:54 PM, Tim Harvey <tharvey@xxxxxxxxxxxxx> wrote: > > > > 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 > > Wim, > > Does the lack of response mean overwhelming approval? > > I haven't heard any valid complaints - what does it take to get this approved? > > Regards, > > Tim I have no objections against the idea and the code itself. But as Guenter pointed out: it would be handy to get feedback from the devicetree maintainers on the above discussion. Kind regards, Wim. -- 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
