On Mon, Aug 24, 2015 at 04:21:24PM +0300, Roger Quadros wrote:
> DRD mode is a reduced functionality OTG mode. In this mode
> we don't support SRP, HNP and dynamic role-swap.
>
> In DRD operation, the controller mode (Host or Peripheral)
> is decided based on the ID pin status. Once a cable plug (Type-A
> or Type-B) is attached the controller selects the state
> and doesn't change till the cable in unplugged and a different
> cable type is inserted.
>
> As we don't need most of the complex OTG states and OTG timers
> we implement a lean DRD state machine in usb-otg.c.
> The DRD state machine is only interested in 2 hardware inputs
> 'id' and 'b_sess_vld'.
>
> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> ---
> drivers/usb/common/usb-otg.c | 178 +++++++++++++++++++++++++++++++++++++++++--
> include/linux/usb/otg-fsm.h | 5 ++
> include/linux/usb/otg.h | 2 +
> 3 files changed, 177 insertions(+), 8 deletions(-)
>
... ...
> +/* Called when entering a DRD state */
> +static void drd_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state)
> +{
> + struct usb_otg *otgd = container_of(fsm, struct usb_otg, fsm);
> +
> + if (fsm->otg->state == new_state)
> + return;
> +
> + fsm->state_changed = 1;
> + dev_dbg(otgd->dev, "otg: set state: %s\n",
> + usb_otg_state_string(new_state));
> + switch (new_state) {
> + case OTG_STATE_B_IDLE:
> + drd_set_protocol(fsm, PROTO_UNDEF);
You didn't address this comment for your previous version.
otg_drv_vbus(fsm, 0);
> + break;
> + case OTG_STATE_B_PERIPHERAL:
> + drd_set_protocol(fsm, PROTO_GADGET);
otg_drv_vbus(fsm, 0);
> + break;
> + case OTG_STATE_A_HOST:
otg_drv_vbus(fsm, 1);
> + drd_set_protocol(fsm, PROTO_HOST);
> + break;
> + case OTG_STATE_UNDEFINED:
> + case OTG_STATE_B_SRP_INIT:
> + case OTG_STATE_B_WAIT_ACON:
> + case OTG_STATE_B_HOST:
> + case OTG_STATE_A_IDLE:
> + case OTG_STATE_A_WAIT_VRISE:
> + case OTG_STATE_A_WAIT_BCON:
> + case OTG_STATE_A_SUSPEND:
> + case OTG_STATE_A_PERIPHERAL:
> + case OTG_STATE_A_WAIT_VFALL:
> + case OTG_STATE_A_VBUS_ERR:
> + default:
> + dev_warn(otgd->dev, "%s: otg: invalid state: %s\n",
> + __func__, usb_otg_state_string(new_state));
> + break;
> + }
> +
> + fsm->otg->state = new_state;
> +}
> +
... ...
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