Re: [PATCH 4/8] arm64: dts: imx8mm-kontron: Fix reg_rst_eth2 and reg_vdd_5v regulators

From: Shawn Guo
Date: Fri Oct 15 2021 - 00:09:19 EST


On Tue, Oct 05, 2021 at 07:06:57PM +0200, Frieder Schrempf wrote:
> On 05.10.21 09:09, Shawn Guo wrote:
> > On Thu, Sep 30, 2021 at 05:56:27PM +0200, Frieder Schrempf wrote:
> >> From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> >>
> >> The regulator reg_vdd_5v represents the fixed 5V supply on the board which
> >> can't be switched off. Mark it as always-on.
> >>
> >> The regulator reg_rst_eth2 should keep the reset signal of the USB ethernet
> >> adapter deassertet anytime. Fix the polarity and mark it as always-on.
> >
> > It seems to be wrong from the beginning that the reset is modelled by a
> > regulator.
>
> Right, but at least at the time when I upstreamed this, there was no way
> to pass the reset GPIO to a USB device driver and using a regulator
> seems to be an accepted workaround as far as I understand.

Do we have the solution in usb driver now? If so, we should probably
switch to that, instead of patching the workaround?

Shawn

>
> >
> >>
> >> Fixes: 21c4f45b335f ("arm64: dts: Add the Kontron i.MX8M Mini SoMs and baseboards")
> >> Cc: stable@xxxxxxxxxxxxxxx
> >> Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> >> ---
> >> arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts | 5 ++++-
> >> 1 file changed, 4 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts b/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
> >> index 62ba3bd08a0c..f2c8ccefd1bf 100644
> >> --- a/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
> >> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-n801x-s.dts
> >> @@ -70,7 +70,9 @@ reg_rst_eth2: regulator-rst-eth2 {
> >> regulator-name = "rst-usb-eth2";
> >> pinctrl-names = "default";
> >> pinctrl-0 = <&pinctrl_usb_eth2>;
> >> - gpio = <&gpio3 2 GPIO_ACTIVE_LOW>;
> >> + gpio = <&gpio3 2 GPIO_ACTIVE_HIGH>;
> >> + enable-active-high;
> >> + regulator-always-on;
> >> };
> >>
> >> reg_vdd_5v: regulator-5v {
> >> @@ -78,6 +80,7 @@ reg_vdd_5v: regulator-5v {
> >> regulator-name = "vdd-5v";
> >> regulator-min-microvolt = <5000000>;
> >> regulator-max-microvolt = <5000000>;
> >> + regulator-always-on;
> >
> > You do not have any on/off control over the regulator. So how does this
> > always-on property make any difference?
>
> Right, this doesn't make a difference and is definitely not a fix, I
> will drop it. Anyway, this regulator is just there for completeness of
> the hardware description.
>
> >
> >> };
> >> };
> >>
> >> --
> >> 2.33.0
> >>