linux-kernel - Re: [PATCH] usb: typec: tcpm/tcpci_maxim: fix non-contaminant CC handling

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Message-ID: <1e650f29c2714b5f390a2bf5edf5920c2975fbac.camel@linaro.org>
Date: Fri, 26 Jul 2024 07:01:13 +0100
From: André Draszik <andre.draszik@...aro.org>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Greg Kroah-Hartman
	 <gregkh@...uxfoundation.org>
Cc: Peter Griffin <peter.griffin@...aro.org>, Tudor Ambarus
 <tudor.ambarus@...aro.org>, Will McVicker <willmcvicker@...gle.com>, 
 kernel-team@...roid.com, RD Babiera <rdbabiera@...gle.com>, Badhri Jagan
 Sridharan <badhri@...gle.com>, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: typec: tcpm/tcpci_maxim: fix non-contaminant CC
 handling

Hi,

On Wed, 2024-07-10 at 07:28 +0100, André Draszik wrote:
> tcpci_maxim currently never triggers the TCPM state machine when CC
> status has not changed due to a contaminant but due to a real
> connection event, i.e. a genuine plug event, meaning the system will
> stay idle and not notify any subscribers.
> 
> The reason is that the initial state of the port is 'toggling', which
> causes _max_tcpci_irq() to only drive the contamination part of the
> TCPM state machine (via tcpm_port_clean()).
> 
> What should happen instead is that if no contamination was detected,
> the TCPM should be notified of the CC change in this case.
> 
> To fix this, we update ...is_contaminant() to also allow its caller to
> determine if more CC processing is required and then call into the TCPM
> as required.
> 
> While at it, add a kernel-doc for max_contaminant_is_contaminant().
> 
> Note: the code has an issue where I2C errors during contaminant
> detection also cause the TCPM state machine to not be updated. This
> commit doesn't change this behaviour and should be addressed by
> follow-up commit(s).
> 
> Signed-off-by: André Draszik <andre.draszik@...aro.org>
> ---
>  drivers/usb/typec/tcpm/maxim_contaminant.c |  7 +++++--
>  drivers/usb/typec/tcpm/tcpci_maxim.h       | 15 ++++++++++++++-
>  drivers/usb/typec/tcpm/tcpci_maxim_core.c  | 12 ++++++++----
>  3 files changed, 27 insertions(+), 7 deletions(-)

Any comments on this patch?

Cheers,
Andre'