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Date: Fri, 30 Sep 2016 06:41:06 +0000
From: Jun Li <jun.li@....com>
To: Guenter Roeck <groeck@...gle.com>
CC: Guenter Roeck <groeck@...omium.org>,
Felipe Balbi <felipe.balbi@...ux.intel.com>,
Chandra Sekhar Anagani <chandra.sekhar.anagani@...el.com>,
Bruce Ashfield <bruce.ashfield@...driver.com>,
Bin Gao <bin.gao@...el.com>,
Pranav Tipnis <pranav.tipnis@...el.com>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)
Hi,
> -----Original Message-----
> From: Guenter Roeck [mailto:groeck@...gle.com]
> Sent: Friday, September 30, 2016 12:37 AM
> To: Jun Li <jun.li@....com>
> Cc: Guenter Roeck <groeck@...omium.org>; Felipe Balbi
> <felipe.balbi@...ux.intel.com>; Chandra Sekhar Anagani
> <chandra.sekhar.anagani@...el.com>; Bruce Ashfield
> <bruce.ashfield@...driver.com>; Bin Gao <bin.gao@...el.com>; Pranav Tipnis
> <pranav.tipnis@...el.com>; Heikki Krogerus
> <heikki.krogerus@...ux.intel.com>; linux-kernel@...r.kernel.org; linux-
> usb@...r.kernel.org
> Subject: Re: [RFC PATCH v3 1/2] usb: typec: USB Type-C Port Manager (tcpm)
>
> On Thu, Sep 29, 2016 at 7:35 AM, Jun Li <jun.li@....com> wrote:
> > Hi Guenter,
> >
> >> -----Original Message-----
> >> From: linux-usb-owner@...r.kernel.org [mailto:linux-usb-
> >> owner@...r.kernel.org] On Behalf Of Guenter Roeck
> >> Sent: Wednesday, August 24, 2016 5:11 AM
> >> To: Felipe Balbi <felipe.balbi@...ux.intel.com>
> >> Cc: Chandra Sekhar Anagani <chandra.sekhar.anagani@...el.com>; Bruce
> >> Ashfield <bruce.ashfield@...driver.com>; Bin Gao <bin.gao@...el.com>;
> >> Pranav Tipnis <pranav.tipnis@...el.com>; Heikki Krogerus
> >> <heikki.krogerus@...ux.intel.com>; linux-kernel@...r.kernel.org;
> >> linux- usb@...r.kernel.org; Guenter Roeck <groeck@...omium.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@...omium.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?
> >
>
> Only while disconnected. It tries to alternatively connect as source and
> as sink (being configured as DRP). Once a CC line state change is reported
> it will transition out. I have a newer version of the patch (not yet
> published) which supports DRP toggling by the TCPC. With that enabled,
> TCPM does not change states until a CC state change is reported.
>
Great, that way will be better, do you plan post your newer patch recently?
Thanks
Li Jun
> Guenter
>
> > 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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