Re: [PATCH v3 0/3] Add support for WDIOF_CARDRESET on TI AM65x

[Li, Hua Qian]

On Thu, 2023-07-13 at 10:21 -0700, Guenter Roeck wrote:
> On 7/13/23 02:51, huaqian.li@xxxxxxxxxxx wrote:
> > From: Li Hua Qian <huaqian.li@xxxxxxxxxxx>
> > 
> > The watchdog hardware of TI AM65X platform does not support
> > WDIOF_CARDRESET feature, add a reserved memory to save the watchdog
> > reset cause, to know if the board reboot is due to a watchdog
> > reset.
> > 
> 
> One thing I keep wondering about: What prevents the Linux kernel from
> treating the special memory area like normal memory ? I would have
> expected
> some usage note, such as that the memory area must be reported as
> reserved
> to the kernel, but I don't see anything like that.
> 
> Guenter

Could you help to suggest how to handle it? 

I am not sure where is a good place to write the usage note. I am
thinking to add it in v4 to DT binding.

Best regards,
Li Hua Qian
> 
> > Changes in v3:
> > - Add memory-region back for the reserved memory, and remove
> > reserved
> >    memory from the watchdog IO address space.
> > - Add changelog.
> > - Link to v2:
> >   
> > https://lore.kernel.org/linux-watchdog/20230711091713.1113010-1-huaqian.li@xxxxxxxxxxx
> > 
> > Changes in v2:
> > - Remove memory-region and memory-size properties, and bind the
> > reserved
> >    memory to watchdog IO address space.
> > - Remove the unnecessary rti_wdt_ioctl.
> > - Fix the mail list
> > - Link to v1:
> >   
> > https://lore.kernel.org/all/3137d87e56ef75ba0b8a923d407b2fecace6ccbd.camel@xxxxxxxxxxx/
> >    v1 had a wrong mail list at the beginning, and the mail thread
> > was
> >    messed up.
> > 
> > Li Hua Qian (3):
> >    dt-bindings: watchdog: ti,rti-wdt: Add support for
> > WDIOF_CARDRESET
> >    arm64: dts: ti: Add reserved memory for watchdog
> >    watchdog:rit_wdt: Add support for WDIOF_CARDRESET
> > 
> >   .../bindings/watchdog/ti,rti-wdt.yaml         | 12 +++++
> >   .../boot/dts/ti/k3-am65-iot2050-common.dtsi   | 10 ++++
> >   drivers/watchdog/rti_wdt.c                    | 51
> > +++++++++++++++++++
> >   3 files changed, 73 insertions(+)
> > 
>