Re: [PATCH v2 2/2] usb: typec: tcpm: Support non-PD mode

Kyle Tso
2021-07-28T02:11:47Z

On Wed, Jul 28, 2021 at 6:46 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 7/27/21 8:13 AM, Kyle Tso wrote:
> > Even if the Type-C controller supports PD, it is doable to disable PD
> > capabilities with the current state machine in TCPM. Without enabling RX
> > in low-level drivers and with skipping the power negotiation, the port
> > is eligible to be a non-PD Type-C port. Use new flags whose values are
> > populated from the device tree to decide the port PD capability. Adding
> > "pd-supported" property in device tree indicates that the port supports
> > PD. If "pd-supported" is not found, "typec-power-opmode" shall be added
> > to specify the advertised Rp value if the port supports SRC role.
> >
> > Signed-off-by: Kyle Tso <kyletso@google.com>
> > ---
> > changes since v1:
> > - Revised the patch to use dt properties
> > - Added back the checks of callbacks set_pd_rx and pd_transmit
> > - Added src_rp to indicate which Rp value should be used in SRC. This
> > variable is derived from dt property "typec-power-opmode"
> >
> > drivers/usb/typec/tcpm/tcpm.c | 108 +++++++++++++++++++++++++---------
> > 1 file changed, 79 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 5b22a1c931a9..4cf77c787f54 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -316,6 +316,7 @@ struct tcpm_port {
> > struct typec_partner *partner;
> >
> > enum typec_cc_status cc_req;
> > + enum typec_cc_status src_rp; /* work only if pd_supported == false */
> >
> > enum typec_cc_status cc1;
> > enum typec_cc_status cc2;
> > @@ -323,6 +324,7 @@ struct tcpm_port {
> >
> > bool attached;
> > bool connected;
> > + bool pd_supported;
> > enum typec_port_type port_type;
> >
> > /*
> > @@ -804,6 +806,7 @@ static void tcpm_apply_rc(struct tcpm_port *port)
> > }
> > }
> >
> > +
> > /*
> > * Determine RP value to set based on maximum current supported
> > * by a port if configured as source.
> > @@ -815,6 +818,9 @@ static enum typec_cc_status tcpm_rp_cc(struct tcpm_port *port)
> > int nr_pdo = port->nr_src_pdo;
> > int i;
> >
> > + if (!port->pd_supported)
> > + return port->src_rp;
> > +
> > /*
> > * Search for first entry with matching voltage.
> > * It should report the maximum supported current.
> > @@ -3568,9 +3574,11 @@ static int tcpm_src_attach(struct tcpm_port *port)
> > if (ret < 0)
> > return ret;
> >
> > - ret = port->tcpc->set_pd_rx(port->tcpc, true);
> > - if (ret < 0)
> > - goto out_disable_mux;
> > + if (port->pd_supported) {
> > + ret = port->tcpc->set_pd_rx(port->tcpc, true);
> > + if (ret < 0)
> > + goto out_disable_mux;
> > + }
> >
> > /*
> > * USB Type-C specification, version 1.2,
> > @@ -3600,7 +3608,8 @@ static int tcpm_src_attach(struct tcpm_port *port)
> > out_disable_vconn:
> > tcpm_set_vconn(port, false);
> > out_disable_pd:
> > - port->tcpc->set_pd_rx(port->tcpc, false);
> > + if (port->pd_supported)
> > + port->tcpc->set_pd_rx(port->tcpc, false);
> > out_disable_mux:
> > tcpm_mux_set(port, TYPEC_STATE_SAFE, USB_ROLE_NONE,
> > TYPEC_ORIENTATION_NONE);
> > @@ -3804,6 +3813,20 @@ static enum typec_pwr_opmode tcpm_get_pwr_opmode(enum typec_cc_status cc)
> > }
> > }
> >
> > +static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
> > +{
> > + switch (opmode) {
> > + case TYPEC_PWR_MODE_USB:
> > + return TYPEC_CC_RP_DEF;
> > + case TYPEC_PWR_MODE_1_5A:
> > + return TYPEC_CC_RP_1_5;
> > + case TYPEC_PWR_MODE_3_0A:
> > + case TYPEC_PWR_MODE_PD:
> > + default:
> > + return TYPEC_CC_RP_3_0;
> > + }
> > +}
> > +
> > static void run_state_machine(struct tcpm_port *port)
> > {
> > int ret;
> > @@ -3914,6 +3937,10 @@ static void run_state_machine(struct tcpm_port *port)
> > if (port->ams == POWER_ROLE_SWAP ||
> > port->ams == FAST_ROLE_SWAP)
> > tcpm_ams_finish(port);
> > + if (!port->pd_supported) {
> > + tcpm_set_state(port, SRC_READY, 0);
> > + break;
> > + }
> > port->upcoming_state = SRC_SEND_CAPABILITIES;
> > tcpm_ams_start(port, POWER_NEGOTIATION);
> > break;
> > @@ -4161,7 +4188,10 @@ static void run_state_machine(struct tcpm_port *port)
> > current_lim = PD_P_SNK_STDBY_MW / 5;
> > tcpm_set_current_limit(port, current_lim, 5000);
> > tcpm_set_charge(port, true);
> > - tcpm_set_state(port, SNK_WAIT_CAPABILITIES, 0);
> > + if (!port->pd_supported)
> > + tcpm_set_state(port, SNK_READY, 0);
> > + else
> > + tcpm_set_state(port, SNK_WAIT_CAPABILITIES, 0);
> > break;
> > }
> > /*
> > @@ -4389,7 +4419,8 @@ static void run_state_machine(struct tcpm_port *port)
> > tcpm_set_vbus(port, true);
> > if (port->ams == HARD_RESET)
> > tcpm_ams_finish(port);
> > - port->tcpc->set_pd_rx(port->tcpc, true);
> > + if (port->pd_supported)
> > + port->tcpc->set_pd_rx(port->tcpc, true);
> > tcpm_set_attached_state(port, true);
> > tcpm_set_state(port, SRC_UNATTACHED, PD_T_PS_SOURCE_ON);
> > break;
> > @@ -5898,6 +5929,7 @@ EXPORT_SYMBOL_GPL(tcpm_tcpc_reset);
> > static int tcpm_fw_get_caps(struct tcpm_port *port,
> > struct fwnode_handle *fwnode)
> > {
> > + const char *opmode_str;
> > const char *cap_str;
> > int ret;
> > u32 mw, frs_current;
> > @@ -5932,22 +5964,36 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
> > return ret;
> > port->typec_caps.type = ret;
> > port->port_type = port->typec_caps.type;
> > + port->pd_supported = fwnode_property_read_bool(fwnode, "pd-supported");
> >
>
> As mentioned in the other patch, I think this needs to be negated.
> Not the variable itself, but the meaning of the property.
>

Makes sense. I will send another patch.

> > port->slow_charger_loop = fwnode_property_read_bool(fwnode, "slow-charger-loop");
>
> It might make sense to move the properties needed with !pd_supported to here
> and return immediately after they are read. This would reduce the number of
> required changes and avoid trying to read irrelevant properties.
> Something like
>
> if (port->port_type != TYPEC_PORT_SRC)
> port->self_powered = fwnode_property_read_bool(fwnode, "self-powered");
>
> if (!port->pd_supported)
> return 0;
>

I will try to modify the flow control as well.

thanks,
Kyle

> > if (port->port_type == TYPEC_PORT_SNK)
> > goto sink;
> >
> > /* Get source pdos */
> > - ret = fwnode_property_count_u32(fwnode, "source-pdos");
> > - if (ret <= 0)
> > - return -EINVAL;
> > + if (port->pd_supported) {
> > + ret = fwnode_property_count_u32(fwnode, "source-pdos");
> > + if (ret <= 0)
> > + return -EINVAL;
> >
> > - port->nr_src_pdo = min(ret, PDO_MAX_OBJECTS);
> > - ret = fwnode_property_read_u32_array(fwnode, "source-pdos",
> > - port->src_pdo, port->nr_src_pdo);
> > - if ((ret < 0) || tcpm_validate_caps(port, port->src_pdo,
> > - port->nr_src_pdo))
> > - return -EINVAL;
> > + port->nr_src_pdo = min(ret, PDO_MAX_OBJECTS);
> > + ret = fwnode_property_read_u32_array(fwnode, "source-pdos",
> > + port->src_pdo, port->nr_src_pdo);
> > + if ((ret < 0) || tcpm_validate_caps(port, port->src_pdo,
> > + port->nr_src_pdo))
> > + return -EINVAL;
> > + } else {
> > + port->nr_src_pdo = 0;
> > + ret = fwnode_property_read_string(fwnode, "typec-power-opmode", &opmode_str);
> > + if (ret == 0) {
> > + ret = typec_find_pwr_opmode(opmode_str);
> > + if (ret < 0)
> > + return ret;
> > + port->src_rp = tcpm_pwr_opmode_to_rp(ret);
> > + } else {
> > + return ret;
> > + }
> > + }
> >
> > if (port->port_type == TYPEC_PORT_SRC)
> > return 0;
> > @@ -5962,25 +6008,29 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
> > return -EINVAL;
> > sink:
> > /* Get sink pdos */
> > - ret = fwnode_property_count_u32(fwnode, "sink-pdos");
> > - if (ret <= 0)
> > - return -EINVAL;
> > + if (port->pd_supported) {
> > + ret = fwnode_property_count_u32(fwnode, "sink-pdos");
> > + if (ret <= 0)
> > + return -EINVAL;
> >
> > - port->nr_snk_pdo = min(ret, PDO_MAX_OBJECTS);
> > - ret = fwnode_property_read_u32_array(fwnode, "sink-pdos",
> > - port->snk_pdo, port->nr_snk_pdo);
> > - if ((ret < 0) || tcpm_validate_caps(port, port->snk_pdo,
> > - port->nr_snk_pdo))
> > - return -EINVAL;
> > + port->nr_snk_pdo = min(ret, PDO_MAX_OBJECTS);
> > + ret = fwnode_property_read_u32_array(fwnode, "sink-pdos",
> > + port->snk_pdo, port->nr_snk_pdo);
> > + if ((ret < 0) || tcpm_validate_caps(port, port->snk_pdo,
> > + port->nr_snk_pdo))
> > + return -EINVAL;
> >
> > - if (fwnode_property_read_u32(fwnode, "op-sink-microwatt", &mw) < 0)
> > - return -EINVAL;
> > - port->operating_snk_mw = mw / 1000;
> > + if (fwnode_property_read_u32(fwnode, "op-sink-microwatt", &mw) < 0)
> > + return -EINVAL;
> > + port->operating_snk_mw = mw / 1000;
> > + } else {
> > + port->nr_snk_pdo = 0;
> > + }
> >
> > port->self_powered = fwnode_property_read_bool(fwnode, "self-powered");
> >
> > - /* FRS can only be supported byb DRP ports */
> > - if (port->port_type == TYPEC_PORT_DRP) {
> > + /* FRS can only be supported by DRP ports */
> > + if (port->port_type == TYPEC_PORT_DRP && port->pd_supported) {
> > ret = fwnode_property_read_u32(fwnode, "new-source-frs-typec-current",
> > &frs_current);
> > if (ret >= 0 && frs_current <= FRS_5V_3A)
> >
>