linux-kernel - Re: Re: [PATCH v2] ARM: dts: sun8i-r40: remove unused GPIO regulator

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Message-ID: <20241220172134.GA9899@lemon.iwr.uni-heidelberg.de>
Date: Fri, 20 Dec 2024 18:21:34 +0100
From: Hermann Lauer <Hermann.Lauer@....uni-heidelberg.de>
To: Icenowy Zheng <uwu@...nowy.me>
Cc: Andre Przywara <andre.przywara@....com>,
	Hermann.Lauer@...-heidelberg.de, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH v2] ARM: dts: sun8i-r40: remove unused GPIO regulator

Hi,

On Sat, Dec 14, 2024 at 03:13:23PM +0800, Icenowy Zheng wrote:
> > CC:ing Icenowy, who added the regulator originally, with commit
> > 0ca12c1ee43c ("ARM: sun8i: r40: add 5V regulator for Banana Pi M2
> > Ultra").
...
> > Icenowy: can you clarify what "newer" version this was referring to
> > in
> > that commit message? That commit in itself doesn't seem to do
> > anything,
> > as the regulator isn't referenced, and it's not always-on. It's only
> > later when the USB nodes were added that it got used?
> > So was PH23 really necessary? As Hermann reports, setting PH23 on a
> > v1.1
> > makes it reboot.

diagnosed that futher now: PH23 is indeed powering the USB-Ports. Whats
happens ist that I powered the board through the micro USB port which turned
out to be limited to 900mA in axp221s. So the setting of reg 0x30 is
the real culprit: Setting the two lowest bits in this register allows
unlimited power over micro usb.

In U-Boot:
 i2c dev 0
 i2c mw 34 30 63

Or power the board through the barrel connector.

In all cases the kernel turns on USB-A power and boots.

> I am not sure, the schematics I have here (which says V1.0) have PH23
> as NC... Well, the M2 Berry schematics have PH23 as 5V EN, maybe I
> messed up M2U and M2B when developing?

While V1.0 didn't need the PH23 setup due to nc, V1.1 needs it. Maybe V1.1
was already on the horizon...

Thanks for the insights and your support, guys.

With seasons greetings
  Hermann