linux-kernel - Re: [PATCH] usb: typec: ucsi: psy: Set current max to 100mA for BC 1.2 and Default

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Message-ID: <CAMFSARe3a+gtsMJzBjpn+1S6jQ3LStWprT599gSN8QxULVmjLA@mail.gmail.com>
Date: Thu, 17 Jul 2025 13:48:50 -0700
From: Jameson Thies <jthies@...gle.com>
To: Benson Leung <bleung@...omium.org>
Cc: heikki.krogerus@...ux.intel.com, gregkh@...uxfoundation.org, 
	hansg@...nel.org, sebastian.reichel@...labora.com, 
	dmitry.baryshkov@....qualcomm.com, madhu.m@...el.com, 
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, bleung@...gle.com
Subject: Re: [PATCH] usb: typec: ucsi: psy: Set current max to 100mA for BC
 1.2 and Default

On Thu, Jul 17, 2025 at 1:08 PM Benson Leung <bleung@...omium.org> wrote:
>
> ucsi_psy_get_current_max would return 0mA as the maximum current if
> UCSI detected a BC or a Default USB Power sporce.
>
> The comment in this function is true that we can't tell the difference
> between DCP/CDP or SDP chargers, but we can guarantee that at least 1-unit
> of USB 1.1/2.0 power is available, which is 100mA, which is a better
> fallback value than 0, which causes some userspaces, including the ChromeOS
> power manager, to regard this as a power source that is not providing
> any power.
>
> In reality, 100mA is guaranteed from all sources in these classes.
>
> Signed-off-by: Benson Leung <bleung@...omium.org>

Reviewed-by: Jameson Thies <jthies@...gle.com>