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SubjectRe: [PATCH v10 2/2] usb: xhci: Add Clear_TT_Buffer
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On 16.5.2019 17.40, Jim Lin wrote:
> USB 2.0 specification chapter 11.17.5 says "as part of endpoint halt
> processing for full-/low-speed endpoints connected via a TT, the host
> software must use the Clear_TT_Buffer request to the TT to ensure
> that the buffer is not in the busy state".
>
> In our case, a full-speed speaker (ConferenceCam) is behind a high-
> speed hub (ConferenceCam Connect), sometimes once we get STALL on a
> request we may continue to get STALL with the folllowing requests,
> like Set_Interface.
>
> Here we invoke usb_hub_clear_tt_buffer() to send Clear_TT_Buffer
> request to the hub of the device for the following Set_Interface
> requests to the device to get ACK successfully.
>
> Signed-off-by: Jim Lin <jilin@nvidia.com>
> ---
> v2: xhci_clear_tt_buffer_complete: add static, shorter indentation
> , remove its claiming in xhci.h
> v3: Add description for clearing_tt (xhci.h)
> v4: Remove clearing_tt flag because hub_tt_work has hub->tt.lock
> to protect for Clear_TT_Buffer to be run serially.
> Remove xhci_clear_tt_buffer_complete as it's not necessary.
> Same reason as the above.
> Extend usb_hub_clear_tt_buffer parameter
> v5: Not extending usb_hub_clear_tt_buffer parameter
> Add description.
> v6: Remove unused parameter slot_id from xhci_clear_hub_tt_buffer
> v7: Add devaddr field in "struct usb_device"
> v8: split as two patches
> v9: no change flag
> v10: Add EP_CLEARING_TT flag
>
> drivers/usb/host/xhci-ring.c | 27 ++++++++++++++++++++++++++-
> drivers/usb/host/xhci.c | 17 +++++++++++++++++
> drivers/usb/host/xhci.h | 5 +++++
> 3 files changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index 9215a28dad40..11d498b6c09b 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -399,7 +399,7 @@ void xhci_ring_ep_doorbell(struct xhci_hcd *xhci,
> * stream once the endpoint is on the HW schedule.
> */
> if ((ep_state & EP_STOP_CMD_PENDING) || (ep_state & SET_DEQ_PENDING) ||
> - (ep_state & EP_HALTED))
> + (ep_state & EP_HALTED) || (ep_state & EP_CLEARING_TT))
> return;
> writel(DB_VALUE(ep_index, stream_id), db_addr);
> /* The CPU has better things to do at this point than wait for a
> @@ -433,6 +433,13 @@ static void ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
> }
> }
>
> +void xhci_ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
> + unsigned int slot_id,
> + unsigned int ep_index)
> +{
> + ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
> +}
> +
> /* Get the right ring for the given slot_id, ep_index and stream_id.
> * If the endpoint supports streams, boundary check the URB's stream ID.
> * If the endpoint doesn't support streams, return the singular endpoint ring.
> @@ -1786,6 +1793,23 @@ struct xhci_segment *trb_in_td(struct xhci_hcd *xhci,
> return NULL;
> }
>
> +static void xhci_clear_hub_tt_buffer(struct xhci_hcd *xhci, struct xhci_td *td,
> + struct xhci_virt_ep *ep)
> +{
> + /*
> + * As part of low/full-speed endpoint-halt processing
> + * we must clear the TT buffer (USB 2.0 specification 11.17.5).
> + */
> + if (td->urb->dev->tt && !usb_pipeint(td->urb->pipe) &&
> + (td->urb->dev->tt->hub != xhci_to_hcd(xhci)->self.root_hub) &&
> + !(ep->ep_state & EP_CLEARING_TT)) {
> + ep->ep_state |= EP_CLEARING_TT;
> + td->urb->ep->hcpriv = td->urb->dev;
> + if (usb_hub_clear_tt_buffer(td->urb))
> + ep->ep_state &= ~EP_CLEARING_TT;
> + }
> +}
> +
> static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
> unsigned int slot_id, unsigned int ep_index,
> unsigned int stream_id, struct xhci_td *td,
> @@ -1804,6 +1828,7 @@ static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
> if (reset_type == EP_HARD_RESET) {
> ep->ep_state |= EP_HARD_CLEAR_TOGGLE;
> xhci_cleanup_stalled_ring(xhci, ep_index, stream_id, td);
> + xhci_clear_hub_tt_buffer(xhci, td, ep);
> }
> xhci_ring_cmd_db(xhci);
> }
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 68b393e5a453..0dc108e61a89 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -5133,6 +5133,22 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
> }
> EXPORT_SYMBOL_GPL(xhci_gen_setup);
>
> +static void xhci_clear_tt_buffer_complete(struct usb_hcd *hcd,
> + struct usb_host_endpoint *ep)
> +{
> + struct xhci_hcd *xhci;
> + struct usb_device *udev;
> + unsigned int slot_id;
> + unsigned int ep_index;
> +
> + xhci = hcd_to_xhci(hcd);
> + udev = (struct usb_device *)ep->hcpriv;
> + slot_id = udev->slot_id;
> + ep_index = xhci_get_endpoint_index(&ep->desc);


spin_lock_irqsave(&xhci->lock, flags); (protecting ep_state)

> + xhci->devs[slot_id]->eps[ep_index].ep_state &= ~EP_CLEARING_TT;
> + xhci_ring_doorbell_for_active_rings(xhci, slot_id, ep_index);

unlock

note:
lock is already taken in xhci_cleanup_halted_endpoint()
so no need to take lock for xhci_clear_hub_tt_buffer()


Other than that this looks good to me.

-Mathias

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