linux-kernel - [PATCH 1/2 v3] tcpm: During PR_SWAP, source caps should be sent only after tSwapSourceStart

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Date:   Tue, 11 Aug 2020 19:29:33 -0700
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Badhri Jagan Sridharan <badhri@...gle.com>
Subject: [PATCH 1/2 v3] tcpm: During PR_SWAP, source caps should be sent only
 after tSwapSourceStart

>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@...gle.com>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
---
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@...ck-us.net>
---
 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 */
-- 
2.28.0.236.gb10cc79966-goog