linux-kernel - Re: [PATCH v2] usb: typec: tcpm: apply vbus before data bringup in tcpm_src

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Message-ID: <2025052122-puzzle-certainly-952e@gregkh>
Date: Wed, 21 May 2025 13:06:46 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: RD Babiera <rdbabiera@...gle.com>
Cc: heikki.krogerus@...ux.intel.com, badhri@...gle.com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v2] usb: typec: tcpm: apply vbus before data bringup in
 tcpm_src_attach

On Thu, May 15, 2025 at 01:40:02AM +0000, RD Babiera wrote:
> This patch fixes Type-C compliance test TD 4.7.6 - Try.SNK DRP Connect
> SNKAS.
> 
> tVbusON has a limit of 275ms when entering SRC_ATTACHED. Compliance
> testers can interpret the TryWait.Src to Attached.Src transition after
> Try.Snk as being in Attached.Src the entire time, so ~170ms is lost
> to the debounce timer.
> 
> Setting the data role can be a costly operation in host mode, and when
> completed after 100ms can cause Type-C compliance test check TD 4.7.5.V.4
> to fail.
> 
> Turn VBUS on before tcpm_set_roles to meet timing requirement.
> 
> Fixes: f0690a25a140 ("staging: typec: USB Type-C Port Manager (tcpm)")
> Cc: stable@...r.kernel.org
> Signed-off-by: RD Babiera <rdbabiera@...gle.com>
> Reviewed-by: Badhri Jagan Sridharan <badhri@...gle.com>
> Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
> Changes since v1:
> * Rebased on top of usb-linus for v6.15

This needs to go into 6.16-rc1 given the lateness of it, sorry.  And it
doesn't apply at all to my usb-next branch :(

thanks,

greg k-h