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SubjectRe: [RFC][PATCH v2 01/13] usb: otg-fsm: Add documentation for struct otg_fsm
On Tue, Apr 14, 2015 at 01:41:48PM +0300, Roger Quadros wrote:
> struct otg_fsm is the interface to the OTG state machine.
>
> Document the input, output and internal state variables.
> Definations are taken from Table 7-2 and Table 7-4 of
> the USB OTG & EH Specification Rev.2.0
>
> Re-arrange some of the members as per use case for more
> clarity.
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> include/linux/usb/otg-fsm.h | 80 +++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 73 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h
> index b6ba1bf..c5b74c5 100644
> --- a/include/linux/usb/otg-fsm.h
> +++ b/include/linux/usb/otg-fsm.h
> @@ -57,37 +57,103 @@ enum otg_fsm_timer {
> NUM_OTG_FSM_TIMERS,
> };
>
> -/* OTG state machine according to the OTG spec */
> +/**
> + * struct otg_fsm - OTG state machine according to the OTG spec
> + *
> + * OTG hardware Inputs
> + *
> + * Common inputs for A and B device

What's the intention you leave two spaces at above line?

> + * @id: TRUE for B-device, FALSE for A-device.
> + * @adp_change: TRUE when current ADP measurement (n) value, compared to the
> + * ADP measurement taken at n-2, differs by more than CADP_THR
> + * @power_up: TRUE when the OTG device first powers up its USB system and
> + * ADP measurement taken if ADP capable
> + *
> + * A-Device state inputs
> + * @a_srp_det: TRUE if the A-device detects SRP
> + * @a_vbus_vld: TRUE when VBUS voltage is in regulation
> + * @b_conn: TRUE if the A-device detects connection from the B-device
> + * @a_bus_resume: TRUE when the B-device detects that the A-device is signaling
> + * a resume (K state)
> + * B-Device state inputs
> + * @a_bus_suspend: TRUE when the B-device detects that the A-device has put the bus into suspend
> + * @a_conn: TRUE if the B-device detects a connection from the A-device
> + * @b_se0_srp: TRUE when the line has been at SE0 for more than the minimum
> + * time before generating SRP
> + * @b_ssend_srp: TRUE when the VBUS has been below VOTG_SESS_VLD for more than
> + * the minimum time before generating SRP
> + * @b_sess_vld: TRUE when the B-device detects that the voltage on VBUS is
> + * above VOTG_SESS_VLD
> + * @test_device: TRUE when the B-device switches to B-Host and detects an OTG test device
> + * FIXME: must be set by host/hub driver

Yes, according to pid/vid pair.

> + *
> + * Application inputs (A-Device)
> + * @a_bus_drop: TRUE when A-device application needs to power down the bus
> + * @a_bus_req: TRUE when A-device application wants to use the bus.
> + * FALSE to suspend the bus
> + *
> + * Application inputs (B-Device)
> + * @b_bus_req: TRUE during the time that the Application running on the
> + * B-device wants to use the bus
> + *
> + * Auxilary inputs
> + * @a_sess_vld: ??

See OTG spec 1.3, and obsolete now.

> + * @b_bus_suspend: ??
> + * @b_bus_resume: ??

They are used at current otg fsm, just for B-host.

> + *
> + * OTG Output status. Read only for users. updated by otg_ops() helpers
> + *
> + * Outputs for Both A and B device
> + * @drv_vbus: TRUE when A-device is driving VBUS
> + * @loc_conn: TRUE when the local device has signaled that it is connected to the bus
> + * @loc_sof: TRUE when the local device is generating activity on the bus
> + * @adp_prb: TRUE when the local device is in the process of doing ADP probing
> + *
> + * Outputs for B-device state
> + * @adp_sns: TRUE when the B-device is in the process of carrying out ADP sensing
> + * @data_pulse: TRUE when the B-device is performing data line pulsing
> + *
> + * Internal Variables
> + *
> + * a_set_b_hnp_en: TRUE when the A-device has successfully set the b_hnp_enable bit in the B-device.
> + * FIXME: OTG fsm uses otg->host->b_hnp_enable instead

a_set_b_hnp_en is for otg 2.0 and it should instead of
otg->host->b_hnp_enable at otg fsm.

> + * b_srp_done: TRUE when the B-device has completed initiating SRP
> + * b_hnp_enable: TRUE when the B-device has accepted the SetFeature(b_hnp_enable) B-device
> + * FIXME: OTG fsm uses otg->gadget->b_hnp_enable instead

Yes

> + * a_clr_err: Asserted (by application ?) to clear a_vbus_err due to an overcurrent condition
> + * and causes the A-device to transition to a_wait_vfall
> + */
> struct otg_fsm {
> /* Input */
> int id;
> int adp_change;
> int power_up;
> - int test_device;
> - int a_bus_drop;
> - int a_bus_req;
> int a_srp_det;
> int a_vbus_vld;
> int b_conn;
> int a_bus_resume;
> int a_bus_suspend;
> int a_conn;
> - int b_bus_req;
> int b_se0_srp;
> int b_ssend_srp;
> int b_sess_vld;
> + int test_device;
> + int a_bus_drop;
> + int a_bus_req;
> + int b_bus_req;
> +
> /* Auxilary inputs */
> int a_sess_vld;
> int b_bus_resume;
> int b_bus_suspend;
>
> /* Output */
> - int data_pulse;
> int drv_vbus;
> int loc_conn;
> int loc_sof;
> int adp_prb;
> int adp_sns;
> + int data_pulse;
>
> /* Internal variables */
> int a_set_b_hnp_en;
> @@ -95,7 +161,7 @@ struct otg_fsm {
> int b_hnp_enable;
> int a_clr_err;
>
> - /* Informative variables */
> + /* Informative variables. All unused as of now */
> int a_bus_drop_inf;
> int a_bus_req_inf;
> int a_clr_err_inf;
> --
> 2.1.0
>

--

Best Regards,
Peter Chen


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