linux-kernel - Re: [PATCH v2 2/2] phy: add NXP PTN3222 eUSB2 to USB2 redriver

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Message-ID: <CAA8EJpoTb_-HtBPv2=FecHvtHYQD4ipqfq3C98ky=qXEXB=_6Q@mail.gmail.com>
Date: Sat, 31 Aug 2024 02:45:05 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Song Xue <quic_songxue@...cinc.com>
Cc: Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, linux-phy@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v2 2/2] phy: add NXP PTN3222 eUSB2 to USB2 redriver

On Sat, 31 Aug 2024 at 02:13, Song Xue <quic_songxue@...cinc.com> wrote:
> On 8/30/2024 4:20 PM, Dmitry Baryshkov wrote:
> > The NXP PTN3222 is the single-port eUSB2 to USB2 redriver that performs
> > translation between eUSB2 and USB2 signalling schemes. It supports all
> > three data rates: Low Speed, Full Speed and High Speed.
> >
> > The reset state enables autonegotiation of the PHY role and of the data
> > rate, so no additional programming is required.
> >
> > Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>
> > Tested-by: Konrad Dybcio <konradybcio@...nel.org>
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> >   drivers/phy/Kconfig           |  11 ++++
> >   drivers/phy/Makefile          |   1 +
> >   drivers/phy/phy-nxp-ptn3222.c | 123 ++++++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 135 insertions(+)

[trimmed]

> > +
> > +MODULE_DESCRIPTION("NXP PTN3222 eUSB2 Redriver driver");
> > +MODULE_LICENSE("GPL");
> >
> The I2C driver just realizes the function on reset and PWR. What about
> other I2C driver function like I2C interface operations,

I don't quite understand what you mean by this. Could you please clarify?

>  auto-suspend,

I think you mean pm_runtime here. It's a valid case, but granted that
it should stay enabled when USB controller is enabled, the gain should
be pretty limited. I'll consider a followup patch implementing
pm_runtime for the sake of being able to disable I2C host if DWC3
controller disables the PHY.

> remote wakeup,

Not supported by design. PTN3222 doesn't have IRQ pins to report
events to the host.

> memory maps etc.

huh?

>  Who will enable these? I think it is not
> incomplete I2C driver, if on someday, ptn3222 is used as I2C device.

Well, I'm using it as an I2C device.

-- 
With best wishes
Dmitry