linux-kernel - Re: [PATCH v2] usb: typec: tpcm: Fix PORT_RESET behavior for self powered devices

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Message-ID: <ZfAaea3+HJ0P2zXn@kuha.fi.intel.com>
Date: Tue, 12 Mar 2024 11:03:53 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Badhri Jagan Sridharan <badhri@...gle.com>
Cc: gregkh@...uxfoundation.org, linux@...ck-us.net, kyletso@...gle.com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	rdbabiera@...gle.com, amitsd@...gle.com, stable@...r.kernel.org,
	frank.wang@...k-chips.com, broonie@...nel.org
Subject: Re: [PATCH v2] usb: typec: tpcm: Fix PORT_RESET behavior for self
 powered devices

On Wed, Feb 28, 2024 at 12:05:12AM +0000, Badhri Jagan Sridharan wrote:
> While commit 69f89168b310 ("usb: typec: tpcm: Fix issues with power being
> removed during reset") fixes the boot issues for bus powered devices such
> as LibreTech Renegade Elite/Firefly, it trades off the CC pins NOT being
> Hi-Zed during errory recovery (i.e PORT_RESET) for devices which are NOT
> bus powered(a.k.a self powered). This change Hi-Zs the CC pins only for
> self powered devices, thus preventing brown out for bus powered devices
> 
> Adhering to spec is gaining more importance due to the Common charger
> initiative enforced by the European Union.
> 
> Quoting from the spec:
>     4.5.2.2.2.1 ErrorRecovery State Requirements
>     The port shall not drive VBUS or VCONN, and shall present a
>     high-impedance to ground (above zOPEN) on its CC1 and CC2 pins.
> 
> Hi-Zing the CC pins is the inteded behavior for PORT_RESET.
> CC pins are set to default state after tErrorRecovery in
> PORT_RESET_WAIT_OFF.
> 
>     4.5.2.2.2.2 Exiting From ErrorRecovery State
>     A Sink shall transition to Unattached.SNK after tErrorRecovery.
>     A Source shall transition to Unattached.SRC after tErrorRecovery.
> 
> Fixes: 69f89168b310 ("usb: typec: tpcm: Fix issues with power being removed during reset")
> Cc: stable@...r.kernel.org
> Cc: Mark Brown <broonie@...nel.org>
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>

Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
> Changes since V1:
> * Fix CC for linux stable
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index c9a78f55ca48..bbe1381232eb 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -5593,8 +5593,11 @@ static void run_state_machine(struct tcpm_port *port)
>  		break;
>  	case PORT_RESET:
>  		tcpm_reset_port(port);
> -		tcpm_set_cc(port, tcpm_default_state(port) == SNK_UNATTACHED ?
> -			    TYPEC_CC_RD : tcpm_rp_cc(port));
> +		if (port->self_powered)
> +			tcpm_set_cc(port, TYPEC_CC_OPEN);
> +		else
> +			tcpm_set_cc(port, tcpm_default_state(port) == SNK_UNATTACHED ?
> +				    TYPEC_CC_RD : tcpm_rp_cc(port));
>  		tcpm_set_state(port, PORT_RESET_WAIT_OFF,
>  			       PD_T_ERROR_RECOVERY);
>  		break;
> 
> base-commit: a560a5672826fc1e057068bda93b3d4c98d037a2
> -- 
> 2.44.0.rc1.240.g4c46232300-goog

-- 
heikki