On Wed, Dec 2, 2015 at 12:54 PM, Tim Harvey [off-list ref] wrote:

On Wed, Dec 2, 2015 at 11:11 AM, Akshay Bhat [off-list ref] wrote:

quoted

On 11/06/2015 05:02 PM, Guenter Roeck wrote:

quoted

On Fri, Nov 06, 2015 at 11:53:42AM -0800, Tim Harvey wrote:

quoted

On Thu, Nov 5, 2015 at 2:23 PM, Guenter Roeck [off-list ref] wrote:

quoted

On Thu, Nov 05, 2015 at 04:19:21PM -0500, Akshay Bhat wrote:

quoted

From: Tim Harvey <tharvey@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 [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@pengutronix.de>
Signed-off-by: Tim Harvey <tharvey@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 ?

quoted

  - 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