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From:   Badhri Jagan Sridharan <badhri@google.com>
Date:   Tue, 11 Aug 2020 19:01:10 -0700
Message-ID: <CAPTae5Jw3ZysWnYj=s7cjU1Hnr3ib7vfCHsgV=1Qq_2EWcUNvg@mail.gmail.com>
Subject: Re: [PATCH v2] tcpm: During PR_SWAP, source caps should be sent only
 after tSwapSourceStart
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        USB <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Aug 11, 2020 at 6:43 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Tue, Aug 11, 2020 at 05:14:39PM -0700, Badhri Jagan Sridharan wrote:
> > From the spec:
> > "6.6.8.1 SwapSourceStartTimer
> > The SwapSourceStartTimer Shall be used by the new Source, after a Power
> > Role Swap or Fast Role Swap, to ensure that it does not send
> > Source_Capabilities Message before the new Sink is ready to receive the
> > Source_Capabilities Message. The new Source Shall Not send the
> > Source_Capabilities Message earlier than tSwapSourceStart after the
> > last bit of the EOP of GoodCRC Message sent in response to the PS_RDY
> > Message sent by the new Source indicating that its power supply is
> > ready."
> >
> > This fixes TD.PD.CP.E3, TD.PD.CP.E4, TD.PD.CP.E5 failures
> >
> > Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
>
> Nit below, otherwise
>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
>
> Note that I wasn't copied on this patch and only noticed it accidentally.

Apologies Guenter ! Error on my side while performing the git
send-email command.
Will make sure that I double check next time.

>
> Guenter
>
> > ---
> > Changes since V1:
> > - Comment on the permissible values of tSwapSourceStart
> > ---
> >  drivers/usb/typec/tcpm/tcpm.c | 2 +-
> >  include/linux/usb/pd.h        | 1 +
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 3ef37202ee37..d38347bd3335 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -3555,7 +3555,7 @@ static void run_state_machine(struct tcpm_port *port)
> >                */
> >               tcpm_set_pwr_role(port, TYPEC_SOURCE);
> >               tcpm_pd_send_control(port, PD_CTRL_PS_RDY);
> > -             tcpm_set_state(port, SRC_STARTUP, 0);
> > +             tcpm_set_state(port, SRC_STARTUP, PD_T_SWAP_SRC_START);
> >               break;
> >
> >       case VCONN_SWAP_ACCEPT:
> > diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
> > index b6c233e79bd4..ed5eed73ccf8 100644
> > --- a/include/linux/usb/pd.h
> > +++ b/include/linux/usb/pd.h
> > @@ -473,6 +473,7 @@ static inline unsigned int rdo_max_power(u32 rdo)
> >  #define PD_T_ERROR_RECOVERY  100     /* minimum 25 is insufficient */
> >  #define PD_T_SRCSWAPSTDBY      625     /* Maximum of 650ms */
> >  #define PD_T_NEWSRC            250     /* Maximum of 275ms */
> > +#define PD_T_SWAP_SRC_START  20     /* Minimum of 20ms */
>
> Odd alignment. Same as with the previous two lines which don't use tabs
> either.
>
> >
> >  #define PD_T_DRP_TRY         100     /* 75 - 150 ms */
> >  #define PD_T_DRP_TRYWAIT     600     /* 400 - 800 ms */