Messages in this thread | | | Subject | Re: [PATCH v3 1/1] usb: xhci: Add Clear_TT_Buffer | From | Mathias Nyman <> | Date | Thu, 2 May 2019 13:56:39 +0300 |
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On 30.4.2019 6.06, 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".
Good point, xhci isn't making sure TT buffers get cleared when they should.
> > 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 add Clear_TT_Buffer for the following Set_Interface requests > 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) > > drivers/usb/host/xhci-ring.c | 28 ++++++++++++++++++++++++++++ > drivers/usb/host/xhci.c | 7 +++++++ > drivers/usb/host/xhci.h | 2 ++ > 3 files changed, 37 insertions(+) > > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c > index 9215a28dad40..02b1ebad81e7 100644 > --- a/drivers/usb/host/xhci-ring.c > +++ b/drivers/usb/host/xhci-ring.c > @@ -1786,6 +1786,33 @@ struct xhci_segment *trb_in_td(struct xhci_hcd *xhci, > return NULL; > } > > +static void xhci_clear_hub_tt_buffer(struct xhci_hcd *xhci, > + unsigned int slot_id, struct xhci_td *td) > +{ > + struct xhci_virt_device *dev; > + struct xhci_slot_ctx *slot_ctx; > + int saved_devnum; > + > + /* > + * 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) && > + !xhci->clearing_tt) { > + xhci->clearing_tt = 1;
one xhci->clearing_tt under is not enough, there might be several HS hubs, or multi TT hubs with halted endpoints at the same time that need TT clearing.
How about a flag per endpoint?
For example Aadding a EP_CLEARING_TT flag for ep_state in struct xhci_virt_ep? just like EP_STOP_CMD_PENDING, or EP_HALTED
> + dev = xhci->devs[slot_id]; > + slot_ctx = xhci_get_slot_ctx(xhci, dev->out_ctx); > + /* Update devnum temporarily for usb_hub_clear_tt_buffer */ > + saved_devnum = td->urb->dev->devnum; > + td->urb->dev->devnum = (int) le32_to_cpu(slot_ctx->dev_state) & > + DEV_ADDR_MASK;
Changing the struct usb_device devnum on the fly seems like a bit of a hack, and probably causes issues elsewhere. Devnum is tied to uevents, usbfs, sysfs etc.
We need another solution, some options:
- Let usb_hub_clear_tt_buffer() figure out address and not just use devnum if host == xhci. - Add address to struct usb_device, (would have both address and devnum), use it when needed. - Provide address as parameter to usb_clear_tt_buffer() (api change, changes other host drivers) - Force devnum to be same as address, usb core can't choose address for xhci devices.
-Mathias
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