[PATCH 6/6] arm64: defconfig: Enable Renesas DA9062 defconfig

[Biju Das]

Hi Geert,

> -----Original Message-----
> From: Geert Uytterhoeven <geert at linux-m68k.org>
> Sent: Monday, December 11, 2023 8:20 AM
> Subject: Re: [PATCH 6/6] arm64: defconfig: Enable Renesas DA9062 defconfig
> 
> Hi Biju,
> 
> On Sun, Dec 10, 2023 at 10:50 AM Biju Das <biju.das.jz at bp.renesas.com>
> wrote:
> > > -----Original Message-----
> > > From: Geert Uytterhoeven <geert at linux-m68k.org>
> > > Sent: Friday, December 1, 2023 3:42 PM
> > > Subject: Re: [PATCH 6/6] arm64: defconfig: Enable Renesas DA9062
> > > defconfig
> > >
> > > On Fri, Dec 1, 2023 at 4:02 PM Biju Das <biju.das.jz at bp.renesas.com>
> > > wrote:
> > > > > From: Geert Uytterhoeven <geert at linux-m68k.org> On Fri, Dec 1,
> > > > > 2023 at 12:09 PM Biju Das <biju.das.jz at bp.renesas.com>
> > > > > wrote:
> > > > > > Enable the config for the Renesas DA9062 PMIC and RTC, as it
> > > > > > is populated on RZ/G2UL SMARC EVK.
> > > > > >
> > > > > > Signed-off-by: Biju Das <biju.das.jz at bp.renesas.com>
> > > > >
> > > > > Thanks for your patch!
> > > > >
> > > > > LGTM, but I would have expected (at least)
> > > > >
> > > > >     CONFIG_INPUT_DA9063_ONKEY=m
> > > > >
> > > > > too, cfr. my comments on patch 5/6.
> > > >
> > > > I have tested this, but I get "da9063-onkey da9062-onkey: error -
> ENXIO:
> > > IRQ ONKEY not found"
> > > > So, I won't be able to test onkey events. So plaaning to disable
> > > > this
> > > node.
> > >
> > > Indeed, currently drivers/input/misc/da9063_onkey.c requires an
> > > interrupt to function.  I wonder if it can be made to work using a
> > > timer and pure polling...
> >
> > Yes, that is possible by either adding a debugfs to enable polling for
> testing.
> >
> > Or
> >
> > a device tree property for adding poll delay, so that one can have
> polling support to test onkey driver.
> 
> I would go for the latter, cfr. poll-interval in
> Documentation/devicetree/bindings/input/gpio-keys.yaml.
> 
> > Basically, on a production system we should avoid polling as it
> unnecessarily wakeup the system.
> 
> Wouldn't polling (by Linux) only happen when the system is already awake?

IIUC, That is an overhead. If there is no load, system goes to suspend mode and
the timer for the polling (SCAN keys) will wakeup the system and same 
process repeats. If we have a PMIC IRQ, this won't happen.

> I think the DA9063 itself handles the onkey when the system is asleep.

I will ask HW person to wire IRQ on PMIC, so that I can check the behaviour.

Cheers,
Biju