linux-kernel - RE: [PATCH] usb: typec: tcpm: Fix sink PDO starting index for PPS APDO selection

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Message-ID: <2E89032DDAA8B9408CB92943514A0337019830B6AA@SW-EX-MBX01.diasemi.com>
Date:   Fri, 20 Jul 2018 14:16:33 +0000
From:   Adam Thomson <Adam.Thomson.Opensource@...semi.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>
CC:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Guenter Roeck <linux@...ck-us.net>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Support Opensource <Support.Opensource@...semi.com>
Subject: RE: [PATCH] usb: typec: tcpm: Fix sink PDO starting index for PPS
 APDO selection

On 20 July 2018 14:59, Greg Kroah-Hartman wrote:

> On Tue, Jul 17, 2018 at 03:36:19PM +0100, Adam Thomson wrote:
> > There is a bug in the sink PDO search code when trying to select
> > a PPS APDO. The current code actually sets the starting index for
> > searching to whatever value 'i' is, rather than choosing index 1
> > to avoid the first PDO (always 5V fixed). As a result, for sources
> > which support PPS but whose PPS APDO index does not match with the
> > supporting sink PPS APDO index for the platform, no valid PPS APDO
> > will be found so this feature will not be permitted.
> >
> > Sadly in testing, both Source and Sink capabilities matched up and
> > this was missed. Code is now updated to correctly set the start
> > index to 1, and testing with additional PPS capable sources show
> > this to work as expected.
> >
> > Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>
> > ---
> >  drivers/usb/typec/tcpm.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
> > index 74e0cda..4f1f421 100644
> > --- a/drivers/usb/typec/tcpm.c
> > +++ b/drivers/usb/typec/tcpm.c
> > @@ -2238,7 +2238,7 @@ static unsigned int tcpm_pd_select_pps_apdo(struct
> tcpm_port *port)
> >  			 * PPS APDO. Again skip the first sink PDO as this will
> >  			 * always be 5V 3A.
> >  			 */
> > -			for (j = i; j < port->nr_snk_pdo; j++) {
> > +			for (j = 1; j < port->nr_snk_pdo; j++) {
> >  				pdo = port->snk_pdo[j];
> >
> >  				switch (pdo_type(pdo)) {
> 
> What commit id does this "fix"?
> 
> Does it need to go into 4.18-final?  To the stable kernels?

Sorry, missed that info. This fixes commit:

2eadc33f40d4c59dd0649f8b6958872d85ad05d7
'typec: tcpm: Add core support for sink side PPS'

This patch only went into v4.18-rc1 so should only be targeted for v4.18-final.

Do you want me to resend with this information added?