linux-kernel - Re: [PATCH RFC 2/2] usb: typec: Add support for Parade PS8830 Type-C Retimer

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Message-ID: <ZvGMCTPqBR0VuHd3@linaro.org>
Date: Mon, 23 Sep 2024 18:40:57 +0300
From: Abel Vesa <abel.vesa@...aro.org>
To: Johan Hovold <johan@...nel.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Rajendra Nayak <quic_rjendra@...cinc.com>,
	Sibi Sankar <quic_sibis@...cinc.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Trilok Soni <quic_tsoni@...cinc.com>, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH RFC 2/2] usb: typec: Add support for Parade PS8830 Type-C
 Retimer

On 24-09-04 15:20:55, Johan Hovold wrote:
> On Tue, Sep 03, 2024 at 09:27:45AM +0200, Johan Hovold wrote:
> > On Thu, Aug 29, 2024 at 09:44:26PM +0300, Abel Vesa wrote:
> > > The Parade PS8830 is a Type-C muti-protocol retimer controlled over I2C.
> > > It provides both altmode and orientation handling.
> > > 
> > > Add a driver with support for the following modes:
> > >  - DP 4lanes
> > >  - USB3
> > >  - DP 2lanes + USB3
> > > 
> > > Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> 
> > > +	retimer->supplies[0].supply = "vdd33";
> > > +	retimer->supplies[1].supply = "vdd18";
> > > +	retimer->supplies[2].supply = "vdd15";
> > 
> > vdd115?
> > 
> > > +	retimer->supplies[3].supply = "vcc";
> 
> I took a look at the schematics and it seems like all but one of the
> above supply names are wrong and that some are missing. "vcc" also does
> not exist in either the binding or dt patches you sent separately.
> 
> From what I can tell the supplies are:
> 
> 	vdd		1.15 V
> 	vdd33		3.3 V
> 	vdd33_cap	3.3 V
> 	vddat		1.15 V
> 	vddar		1.15 V
> 	vddio		1.8 V

The schematics seem to suggest that vdd, vddat and vddar are all
supplied by the 1.15V supply. As for the vdd33 and vdd33_cap, their
seem to be supplied by the 3.3V supply.

> 
> Also, have you checked that there are no ordering constraints between
> the supplies?

The documentation seems to suggest that there are some timing as well as
ordering contrains, yes. I can't tell for sure if that is really needed
or not.

Thanks for reviewing.

> 
> Johan
> 

Abel