linux-kernel - Re: [PATCH v2 0/2] usb: typec: Add new driver for Parade PS8830 Type-C Retimer

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Message-ID: <ZxdTdqs2ReKwoFfb@hovoldconsulting.com>
Date: Tue, 22 Oct 2024 09:25:42 +0200
From: Johan Hovold <johan@...nel.org>
To: Abel Vesa <abel.vesa@...aro.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>, linux-arm-msm@...r.kernel.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 v2 0/2] usb: typec: Add new driver for Parade PS8830
 Type-C Retimer

On Thu, Oct 17, 2024 at 11:25:20AM +0300, Abel Vesa wrote:
> On 24-10-17 08:00:44, Johan Hovold wrote:

> > I can confirm that marking the regulators as having been left on by the
> > bootloader so that they are not disabled temporarily during boot indeed
> > fixes the coldplug issue here.
> > 
> > That however makes me wonder whether something is missing in the driver
> > so that it still relies on setup having been done by the boot firmware.
> > 
> > Have you tried actually asserting reset during probe to verify that
> > driver can configure the retimers itself without relying on the boot
> > firmware?
> 
> We do not want to reset the retimers on probe because we won't be able
> to figure out the orientation config until next pmic glink notify comes.
> The pmic glink notify only triggers on USB event, which never comes
> until you replug the device. So in order to have coldplug orientation
> configured correctly in the retimer, we need to make sure the retimer
> holds state until unplug.

Ok, thanks for clarifying. As we've discussed off-list it should be
possible to retrieve the orientation from the orientation gpios, but I'm
sure there are bits missing in the kernel for propagating that
information to the retimers currently.

If I understood you correctly you did reset and reinitialise the
retimers in v1, which is useful during development at least to make sure
that the driver is complete.

Johan