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SubjectRE: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)
Date
Hi Guenter,

> -----Original Message-----
> From: linux-usb-owner@vger.kernel.org [mailto:linux-usb-
> owner@vger.kernel.org] On Behalf Of Guenter Roeck
> Sent: Wednesday, August 24, 2016 5:11 AM
> To: Felipe Balbi <felipe.balbi@linux.intel.com>
> Cc: Chandra Sekhar Anagani <chandra.sekhar.anagani@intel.com>; Bruce
> Ashfield <bruce.ashfield@windriver.com>; Bin Gao <bin.gao@intel.com>;
> Pranav Tipnis <pranav.tipnis@intel.com>; Heikki Krogerus
> <heikki.krogerus@linux.intel.com>; linux-kernel@vger.kernel.org; linux-
> usb@vger.kernel.org; Guenter Roeck <groeck@chromium.org>
> Subject: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)
>
> This driver implements the USB Type-C Power Delivery state machine
> for both source and sink ports. Alternate mode support is not
> fully implemented.
>
> The driver attaches to the USB Type-C class code implemented in
> the following patches.
>
> usb: typec: add driver for Intel Whiskey Cove PMIC USB Type-C PHY
> usb: USB Type-C connector class
>
> This driver only implements the state machine. Lower level drivers are
> responsible for
> - Reporting VBUS status and activating VBUS
> - Setting CC lines and providing CC line status
> - Setting line polarity
> - Activating and deactivating VCONN
> - Setting the current limit
> - Activating and deactivating PD message transfers
> - Sending and receiving PD messages
>
> The driver provides both a functional API as well as callbacks for
> lower level drivers.
>
> Signed-off-by: Guenter Roeck <groeck@chromium.org>
> ---
> v3:
> - Improve TCPM state machine resiliency if there are spurious CC line
> changes
> while the state machine is in a transient change (waiting for a timeout)
> - Update current limit after CC voltage level changes on a port which is
> not
> PD capable.
>
> v2:
> - Only update polarity if setting it was successful
> If setting the CC line polarity in the driver was not successful,
> don't update the internal polarity state.
> - All PD messages are little endian; convert to and from CPU endianness.
> - Avoid comparisons against NULL.
> - Use u8/u16/u32 instead of uint8_t/uint16_t/uint32_t consistently.
> - Callbacks into tcpm need to be lockless to avoid timing problems
> in low level drivers.
> - Simplify callbacks; tcpm can request the current state of cc/vbus
> when it is ready to use it.
>
> drivers/usb/typec/Kconfig | 7 +
> drivers/usb/typec/Makefile | 1 +
> drivers/usb/typec/tcpm.c | 3163
> ++++++++++++++++++++++++++++++++++++++++++++
> drivers/usb/typec/tcpm.h | 137 ++
> include/linux/usb/pd.h | 282 ++++
> include/linux/usb/pd_bdo.h | 31 +
> include/linux/usb/pd_vdo.h | 412 ++++++
> 7 files changed, 4033 insertions(+)
> create mode 100644 drivers/usb/typec/tcpm.c
> create mode 100644 drivers/usb/typec/tcpm.h
> create mode 100644 include/linux/usb/pd.h
> create mode 100644 include/linux/usb/pd_bdo.h
> create mode 100644 include/linux/usb/pd_vdo.h
>

...

> +
> +static void run_state_machine(struct tcpm_port *port)
> +{
> + int ret;
> +
> + port->enter_state = port->state;
> + switch (port->state) {
> + /* SRC states */
> + case SRC_UNATTACHED:
> + tcpm_swap_complete(port, -ENOTCONN);
> + tcpm_src_detach(port);
> + tcpm_set_cc(port, TYPEC_CC_RP_DEF);
> + if (port->typec_caps.type == TYPEC_PORT_DRP)
> + tcpm_set_state(port, SNK_UNATTACHED, PD_T_DRP_SNK);

With this and below, after disconnect, the DRP port state machine will be
in infinite loop of state transition between SRC_UNATTACHED <--> SNK_UNATTACHED,
correct?

Li Jun
...

> + /* SNK states */
> + case SNK_UNATTACHED:
> + tcpm_swap_complete(port, -ENOTCONN);
> + tcpm_snk_detach(port);
> + tcpm_set_cc(port, TYPEC_CC_RD);
> + if (port->typec_caps.type == TYPEC_PORT_DRP)
> + tcpm_set_state(port, SRC_UNATTACHED, PD_T_DRP_SRC);
> + break;
>

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