Re: [PATCH 1/2] usb: mtu3: fix ep0's stall of out data stage

[Chunfeng Yun <chunfeng.yun@mediatek.com>]

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));
> 
> 
>