linux-kernel - Re: [PATCH] usb: typec: ucsi: psy: Set max current to zero when disconnected

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Message-ID: <abd715e2-6edd-4f35-a308-d2ee9a5ca334@panix.com>
Date: Thu, 16 Oct 2025 17:26:40 -0700
From: Kenneth Crudup <kenny@...ix.com>
To: Jameson Thies <jthies@...gle.com>, heikki.krogerus@...ux.intel.com,
 linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
 Kenneth C <kenny@...ix.com>
Cc: dmitry.baryshkov@....qualcomm.com, bleung@...omium.org,
 gregkh@...uxfoundation.org, akuchynski@...omium.org,
 abhishekpandit@...omium.org, sebastian.reichel@...labora.com,
 linux-pm@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] usb: typec: ucsi: psy: Set max current to zero when
 disconnected


I wonder if this is the reason my (Kubuntu 25.04, FWIW) system will 
sometimes show the battery icon as "Charging" even when it's discharging 
(or nothing is plugged into either USB-C port)?

-Kenny

On 10/16/25 17:00, Jameson Thies wrote:
> The ucsi_psy_get_current_max function defaults to 0.1A when it is not
> clear how much current the partner device can support. But this does
> not check the port is connected, and will report 0.1A max current when
> nothing is connected. Update ucsi_psy_get_current_max to report 0A when
> there is no connection.
> 
> Fixes: af833e7f7db3 ("usb: typec: ucsi: psy: Set current max to 100mA for BC 1.2 and Default")
> Signed-off-by: Jameson Thies <jthies@...gle.com>
> Reviewed-by: Benson Leung <bleung@...omium.org>
> Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
>   drivers/usb/typec/ucsi/psy.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/usb/typec/ucsi/psy.c b/drivers/usb/typec/ucsi/psy.c
> index 62a9d68bb66d..8ae900c8c132 100644
> --- a/drivers/usb/typec/ucsi/psy.c
> +++ b/drivers/usb/typec/ucsi/psy.c
> @@ -145,6 +145,11 @@ static int ucsi_psy_get_current_max(struct ucsi_connector *con,
>   {
>   	u32 pdo;
>   
> +	if (!UCSI_CONSTAT(con, CONNECTED)) {
> +		val->intval = 0;
> +		return 0;
> +	}
> +
>   	switch (UCSI_CONSTAT(con, PWR_OPMODE)) {
>   	case UCSI_CONSTAT_PWR_OPMODE_PD:
>   		if (con->num_pdos > 0) {
> 
> base-commit: e40b984b6c4ce3f80814f39f86f87b2a48f2e662

-- 
Kenneth R. Crudup / Sr. SW Engineer, Scott County Consulting, Orange 
County CA