linux-kernel - Re: [PATCH] usb: typec: tcpm: Fix APDO PPS order checking to be based on voltage

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Date:   Fri, 21 Sep 2018 08:52:24 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, support.opensource@...semi.com
Subject: Re: [PATCH] usb: typec: tcpm: Fix APDO PPS order checking to be
 based on voltage

On Fri, Sep 21, 2018 at 04:04:11PM +0100, Adam Thomson wrote:
> Current code mistakenly checks against max current to determine
> order but this should be max voltage. This commit fixes the issue
> so order is correctly determined, thus avoiding failure based on
> a higher voltage PPS APDO having a lower maximum current output,
> which is actually valid.
> 
> Fixes: 2eadc33f40d4 ("typec: tcpm: Add core support for sink side PPS")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>

Makes sense.

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> Code based on usb-testing branch (ae8a2ca8a2215c7e31e6d874f7303801bb15fbb)
> 
>  drivers/usb/typec/tcpm/tcpm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 4f1f421..c11b3be 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -1430,8 +1430,8 @@ static enum pdo_err tcpm_caps_err(struct tcpm_port *port, const u32 *pdo,
>  				if (pdo_apdo_type(pdo[i]) != APDO_TYPE_PPS)
>  					break;
>  
> -				if (pdo_pps_apdo_max_current(pdo[i]) <
> -				    pdo_pps_apdo_max_current(pdo[i - 1]))
> +				if (pdo_pps_apdo_max_voltage(pdo[i]) <
> +				    pdo_pps_apdo_max_voltage(pdo[i - 1]))
>  					return PDO_ERR_PPS_APDO_NOT_SORTED;
>  				else if (pdo_pps_apdo_min_voltage(pdo[i]) ==
>  					  pdo_pps_apdo_min_voltage(pdo[i - 1]) &&
> -- 
> 1.9.1
>