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    SubjectRe: [PATCH 1/2] usb: mtu3: fix ep0's stall of out data stage
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    On Wed, 2022-09-28 at 15:43 +0200, AngeloGioacchino Del Regno wrote:
    > Il 28/09/22 11:17, Chunfeng Yun ha scritto:
    > > It happens when enable uvc function, the flow as below:
    > > the controller switch to data stage, then call
    > > -> foward_to_driver() -> composite_setup() ->
    > > uvc_function_setup(),
    > > it send out an event to user layer to notify it call
    > > -> ioctl() -> uvc_send_response() -> usb_ep_queue(),
    > > but before the user call ioctl to queue ep0's buffer, the host
    > > already send
    > > out data, but the controller find that no buffer is queued to
    > > receive data,
    > > it send out STALL handshake.
    > >
    > > To fix the issue, don't send out ACK of setup stage to switch to
    > > out data
    > > stage until the buffer is available.
    > >
    > > Cc: <Stable@vger.kernel.org>
    > > Reported-by: Min Guo <min.guo@mediatek.com>
    > > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
    > > ---
    > > drivers/usb/mtu3/mtu3.h | 4 ++++
    > > drivers/usb/mtu3/mtu3_gadget_ep0.c | 22 +++++++++++++++++++---
    > > 2 files changed, 23 insertions(+), 3 deletions(-)
    > >
    > > diff --git a/drivers/usb/mtu3/mtu3.h b/drivers/usb/mtu3/mtu3.h
    > > index 2d7b57e07eee..6b64ad17724d 100644
    > > --- a/drivers/usb/mtu3/mtu3.h
    > > +++ b/drivers/usb/mtu3/mtu3.h
    > > @@ -318,6 +318,9 @@ static inline struct ssusb_mtk
    > > *dev_to_ssusb(struct device *dev)
    > > * for GET_STATUS and SET_SEL
    > > * @setup_buf: ep0 response buffer for GET_STATUS and SET_SEL
    > > requests
    > > * @u3_capable: is capable of supporting USB3
    > > + * @delayed_setup: delay the setup stage to avoid STALL handshake
    > > in
    > > + * out data stage due to the class driver doesn't queue
    > > buffer
    > > + * before the host send out data
    > > */
    > > struct mtu3 {
    > > spinlock_t lock;
    > > @@ -360,6 +363,7 @@ struct mtu3 {
    > > unsigned connected:1;
    > > unsigned async_callbacks:1;
    > > unsigned separate_fifo:1;
    > > + unsigned delayed_setup:1;
    > >
    > > u8 address;
    > > u8 test_mode_nr;
    > > diff --git a/drivers/usb/mtu3/mtu3_gadget_ep0.c
    > > b/drivers/usb/mtu3/mtu3_gadget_ep0.c
    > > index e4fd1bb14a55..f7a71cc83e15 100644
    > > --- a/drivers/usb/mtu3/mtu3_gadget_ep0.c
    > > +++ b/drivers/usb/mtu3/mtu3_gadget_ep0.c
    > > @@ -162,6 +162,19 @@ static void ep0_do_status_stage(struct mtu3
    > > *mtu)
    > > mtu3_writel(mbase, U3D_EP0CSR, value | EP0_SETUPPKTRDY |
    > > EP0_DATAEND);
    > > }
    > >
    > > +/* delay sending out ACK of setup stage to wait for OUT buffer
    > > queued */
    > > +static void ep0_setup_stage_send_ack(struct mtu3 *mtu)
    > > +{
    > > + void __iomem *mbase = mtu->mac_base;
    > > + u32 value;
    > > +
    > > + if (mtu->delayed_setup) {
    > > + value = mtu3_readl(mbase, U3D_EP0CSR) & EP0_W1C_BITS;
    > > + mtu3_writel(mbase, U3D_EP0CSR, value |
    > > EP0_SETUPPKTRDY);
    > > + mtu->delayed_setup = 0;
    > > + }
    > > +}
    > > +
    > > static int ep0_queue(struct mtu3_ep *mep0, struct mtu3_request
    > > *mreq);
    > >
    > > static void ep0_dummy_complete(struct usb_ep *ep, struct
    > > usb_request *req)
    > > @@ -628,8 +641,9 @@ static void ep0_read_setup(struct mtu3 *mtu,
    > > struct usb_ctrlrequest *setup)
    > > csr | EP0_SETUPPKTRDY | EP0_DPHTX);
    > > mtu->ep0_state = MU3D_EP0_STATE_TX;
    > > } else {
    > > - mtu3_writel(mtu->mac_base, U3D_EP0CSR,
    > > - (csr | EP0_SETUPPKTRDY) & (~EP0_DPHTX));
    > > + mtu3_writel(mtu->mac_base, U3D_EP0CSR, csr &
    > > ~EP0_DPHTX);
    > > + /* send ACK when the buffer is queued */
    > > + mtu->delayed_setup = 1;
    >
    > I don't think that you need this variable: you're calling the
    > function
    > ep0_setup_stage_send_ack() only when ep0_state == MU3D_EP0_STATE_RX
    > in
    > ep0_queue()...
    >
    > ..so you'll never get a call to ep0_setup_stage_send_ack() with
    > delayed_setup == 0!
    I'll abandon this patch, and try to use delayed_status as suggested by
    Alan, thanks a lot

    >
    > Regards,
    > Angelo
    >
    > > mtu->ep0_state = MU3D_EP0_STATE_RX;
    > > }
    > > }
    > > @@ -804,9 +818,11 @@ static int ep0_queue(struct mtu3_ep *mep,
    > > struct mtu3_request *mreq)
    > >
    > > switch (mtu->ep0_state) {
    > > case MU3D_EP0_STATE_SETUP:
    > > - case MU3D_EP0_STATE_RX: /* control-OUT data */
    > > case MU3D_EP0_STATE_TX: /* control-IN data */
    > > break;
    > > + case MU3D_EP0_STATE_RX: /* control-OUT data */
    > > + ep0_setup_stage_send_ack(mtu);
    > > + break;
    > > default:
    > > dev_err(mtu->dev, "%s, error in ep0 state %s\n",
    > > __func__,
    > > decode_ep0_state(mtu));
    >
    >
    >

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