linux-kernel - Re: [PATCH v2 3/4] usb: typec: ucsi: Set sink path based on UCSI charge control

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Message-ID: <CAMFSARc8D2q2YO6-Mz7jDQv15Yc9f5U7eCXaFTPjLJu_UMXwcQ@mail.gmail.com>
Date: Thu, 25 Jul 2024 12:11:28 -0700
From: Jameson Thies <jthies@...gle.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Sebastian Reichel <sre@...nel.org>, heikki.krogerus@...ux.intel.com, 
	linux-usb@...r.kernel.org, bleung@...gle.com, abhishekpandit@...omium.org, 
	andersson@...nel.org, fabrice.gasnier@...s.st.com, gregkh@...uxfoundation.org, 
	hdegoede@...hat.com, neil.armstrong@...aro.org, rajaram.regupathy@...el.com, 
	saranya.gopal@...el.com, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 3/4] usb: typec: ucsi: Set sink path based on UCSI
 charge control

Hi Dmitry,
thank you for your feedback on this patch. The intention here is to
allow power source selection through the UCSI driver. The existing
typec operation wouldn't work here because setting the power roles
alone won't set the charge source. That's also why there is no
pr_set(TYPEC_SOURCE) call for a negative value. It should disable
charging from that port, but it doesn't need to change the power role.
But I take your point that writing positive/negative values to
charge_control_limit_max is not an intuitive way to enable this
functionality.

Thanks for catching this issues with UCSI version and inconsistencies
between sysfs and system state. I need to revisit the design here.
I'll remove this patch from the V3 series and take another look at how
we could implement power source selection.

Thanks,
Jameson