On Mon, Aug 17, 2020 at 11:38:27AM -0700, Badhri Jagan Sridharan wrote: > The patch addresses the compliance test failures while running > TD.PD.CP.E3, TD.PD.CP.E4, TD.PD.CP.E5 of the "Deterministic PD > Compliance MOI" test plan published in https://www.usb.org/usbc. > For a product to be Type-C compliant, it's expected that these tests > are run on usb.org certified Type-C compliance tester as mentioned in > https://www.usb.org/usbc. > > The purpose of the tests TD.PD.CP.E3, TD.PD.CP.E4, TD.PD.CP.E5 is to > verify the PR_SWAP response of the device. While doing so, the test > asserts that Source Capabilities message is NOT received from the test > device within tSwapSourceStart min (20 ms) from the time the last bit > of GoodCRC corresponding to the RS_RDY message sent by the UUT was > sent. If it does then the test fails. > > This is in line with the requirements from the USB Power Delivery > Specification Revision 3.0, Version 1.2: > "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." > > The patch makes sure that TCPM does not send the Source_Capabilities > Message within tSwapSourceStart(20ms) by transitioning into > SRC_STARTUP only after tSwapSourceStart(20ms). > > Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx> > Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx> Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > --- > Changes since V1: > - Comment on the permissible values of tSwapSourceStart > > Changes since V2: > - Fixing alignment issue pointed out by Guenter. > - Added Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx> > > Changes since V3: > - Updated commit description and made it elaborate to address Heikki's > suggestion. > --- > 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..1df895e4680b 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 */ > > #define PD_T_DRP_TRY 100 /* 75 - 150 ms */ > #define PD_T_DRP_TRYWAIT 600 /* 400 - 800 ms */ thanks, -- heikki
