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    Subject[PATCH 5.4 042/214] usb: typec: tcpm: During PR_SWAP, source caps should be sent only after tSwapSourceStart
    Date
    From: Badhri Jagan Sridharan <badhri@google.com>

    [ Upstream commit 6bbe2a90a0bb4af8dd99c3565e907fe9b5e7fd88 ]

    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@google.com>
    Reviewed-by: Guenter Roeck <linux@roeck-us.net>
    Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
    Link: https://lore.kernel.org/r/20200817183828.1895015-1-badhri@google.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 355a2c7fac0b4..16e124753df72 100644
    --- a/drivers/usb/typec/tcpm/tcpm.c
    +++ b/drivers/usb/typec/tcpm/tcpm.c
    @@ -3482,7 +3482,7 @@ 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 145c38e351c25..6655ce32feff1 100644
    --- a/include/linux/usb/pd.h
    +++ b/include/linux/usb/pd.h
    @@ -442,6 +442,7 @@ 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 */
    --
    2.27.0


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