linux-kernel - Re: [PATCH] usb: typec: tpcm: Fix issues with power being removed during reset

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Date: Sat, 17 Feb 2024 16:54:35 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Mark Brown <broonie@...nel.org>
Cc: Guenter Roeck <linux@...ck-us.net>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Badhri Jagan Sridharan <badhri@...gle.com>,
	Gábor Stefanik <netrolller.3d@...il.com>,
	rdbabiera@...gle.com, amitsd@...gle.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: typec: tpcm: Fix issues with power being removed
 during reset

On Mon, Feb 12, 2024 at 06:42:13PM +0000, Mark Brown wrote:
> Since the merge of b717dfbf73e8 ("Revert "usb: typec: tcpm: fix
> cc role at port reset"") into mainline the LibreTech Renegade
> Elite/Firefly has died during boot, the main symptom observed in testing
> is a sudden stop in console output.  Gábor Stefanik identified in review
> that the patch would cause power to be removed from devices without
> batteries (like this board), observing that while the patch is correct
> according to the spec this appears to be an oversight in the spec.
> 
> Given that the change makes previously working systems unusable let's
> revert it, there was some discussion of identifying systems that have
> alternative power and implementing the standards conforming behaviour in
> only that case.
> 
> Fixes: b717dfbf73e8 ("Revert "usb: typec: tcpm: fix cc role at port reset"")
> Signed-off-by: Mark Brown <broonie@...nel.org>
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index f7d7daa60c8d..a0978ed1a257 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4876,7 +4876,8 @@ static void run_state_machine(struct tcpm_port *port)
>  		break;
>  	case PORT_RESET:
>  		tcpm_reset_port(port);
> -		tcpm_set_cc(port, TYPEC_CC_OPEN);
> +		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;
> 

Dueling reverts, fun!

:(

Badhri, can you either ack this, or submit your proposed change so as to
get this back working again?

thanks,

greg k-h