2020-08-20 23:38:50

by Azhar Shaikh

Subject: [PATCH v4 3/3] platform/chrome: cros_ec_typec: Re-order connector configuration steps

As per USB Type-C Spec R2.0 section 4.5.1.2 (Connecting Sources and Sinks)
and section 4.5.2.2 (Connection State Machine Requirements), the typical
flow for configuring a device connected to a typeC port is as below:

1. Source/sink detection
2. Orientation
3. Data role
4. VCONN
5. VBUS (USB Type-C currents)
6. The connector is now configured. We can start the PD communication
that should lead into configuration of the mux if we enter a mode.

But in existing code data role was set after the connector and mux are
already configured. So fix this by following the spec to set the data
role before the connector and mux are configured.

Signed-off-by: Azhar Shaikh <[email protected]>
---
Changes in v4:
- No change

Changes in v3:
- New patch added

drivers/platform/chrome/cros_ec_typec.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 2b43e1176e73..9e4fad9ca59e 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -516,6 +516,12 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
if (ret)
return ret;

+ ret = usb_role_switch_set_role(typec->ports[port_num]->role_sw,
+ pd_ctrl->role & PD_CTRL_RESP_ROLE_DATA
+ ? USB_ROLE_HOST : USB_ROLE_DEVICE);
+ if (ret)
+ return ret;
+
if (mux_flags & USB_PD_MUX_TBT_COMPAT_ENABLED) {
ret = cros_typec_enable_tbt(typec, port_num, pd_ctrl);
} else if (mux_flags & USB_PD_MUX_DP_ENABLED) {
@@ -533,12 +539,7 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
ret = -ENOTSUPP;
}

- if (ret)
- return ret;
-
- return usb_role_switch_set_role(typec->ports[port_num]->role_sw,
- pd_ctrl->role & PD_CTRL_RESP_ROLE_DATA
- ? USB_ROLE_HOST : USB_ROLE_DEVICE);
+ return ret;
}

static int cros_typec_port_update(struct cros_typec_data *typec, int port_num)
--
2.17.1

2020-08-21 00:04:42

by Prashant Malani

Subject: Re: [PATCH v4 3/3] platform/chrome: cros_ec_typec: Re-order connector configuration steps

On Thu, Aug 20, 2020 at 04:38:32PM -0700, Azhar Shaikh wrote:
> As per USB Type-C Spec R2.0 section 4.5.1.2 (Connecting Sources and Sinks)
> and section 4.5.2.2 (Connection State Machine Requirements), the typical
> flow for configuring a device connected to a typeC port is as below:
>
> 1. Source/sink detection
> 2. Orientation
> 3. Data role
> 4. VCONN
> 5. VBUS (USB Type-C currents)
> 6. The connector is now configured. We can start the PD communication
> that should lead into configuration of the mux if we enter a mode.
>
> But in existing code data role was set after the connector and mux are
> already configured. So fix this by following the spec to set the data
> role before the connector and mux are configured.
>
> Signed-off-by: Azhar Shaikh <[email protected]>
To be clear, I still maintain that the quoted section pertains to
*detection* of those various properties (which is handled by the TCPM in
the Chrome OS EC), and not any ordering for setting switches etc.

That said, I'm not opposed to the re-ordering, so:
Reviewed-by: Prashant Malani <[email protected]>
> ---
> Changes in v4:
> - No change
>
> Changes in v3:
> - New patch added
>
> drivers/platform/chrome/cros_ec_typec.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> index 2b43e1176e73..9e4fad9ca59e 100644
> --- a/drivers/platform/chrome/cros_ec_typec.c
> +++ b/drivers/platform/chrome/cros_ec_typec.c
> @@ -516,6 +516,12 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
> if (ret)
> return ret;
>
> + ret = usb_role_switch_set_role(typec->ports[port_num]->role_sw,
> + pd_ctrl->role & PD_CTRL_RESP_ROLE_DATA
> + ? USB_ROLE_HOST : USB_ROLE_DEVICE);
> + if (ret)
> + return ret;
> +
> if (mux_flags & USB_PD_MUX_TBT_COMPAT_ENABLED) {
> ret = cros_typec_enable_tbt(typec, port_num, pd_ctrl);
> } else if (mux_flags & USB_PD_MUX_DP_ENABLED) {
> @@ -533,12 +539,7 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
> ret = -ENOTSUPP;
> }
>
> - if (ret)
> - return ret;
> -
> - return usb_role_switch_set_role(typec->ports[port_num]->role_sw,
> - pd_ctrl->role & PD_CTRL_RESP_ROLE_DATA
> - ? USB_ROLE_HOST : USB_ROLE_DEVICE);
> + return ret;
> }
>
> static int cros_typec_port_update(struct cros_typec_data *typec, int port_num)
> --
> 2.17.1
>