| Message ID | ed5ddb78abd157ef2bb9317545b9fec63c6a5b66.1618014279.git.Thinh.Nguyen@synopsys.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | usb: Set quirks for xhci/dwc3 host mode | expand |
On 10.4.2021 3.47, Thinh Nguyen wrote: > DWC_usb31 host version 1.90a and prior undercalculates the bandwidth > available for interrupt endpoints. The controller will return bandwidth > error on config endpoint commands if there are already 6 or more > fullspeed interrupt endpoints with bInterval of 4 (or 4ms) associated > with a single fullspeed bus instance (BI). > > To workaround this, configure and use the endpoint at a shorter > interrupt interval. Lower the ep_ctx interval from 5 to 4 (or 2ms) > for interrupt endpoints of the fullspeed BI. Note: we have not observed > functional impact to the fullspeed devices by lowering the interrupt > service interval (at least for a few devices that we tested). > > To simplify the workaround, let's just check and apply the workaround if > the endpoint is a fullspeed interrupt endpoint with interval of 4ms and > if the top parent device is also operating in fullspeed (i.e. associated > with fullspeed BI). > > Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> > --- > Changes in v2: > - None > > Note: > Checkpatch will give a warning below for getting top_dev: > WARNING: suspect code indent for conditional statements > > Since this logic is done everywhere else in the driver, I'm keeping it > consistent here. > > drivers/usb/host/xhci-mem.c | 23 +++++++++++++++++++++++ > include/linux/usb/xhci-quirks.h | 1 + > 2 files changed, 24 insertions(+) > > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c > index 1053b43008e4..e01d0ddb012a 100644 > --- a/drivers/usb/host/xhci-mem.c > +++ b/drivers/usb/host/xhci-mem.c > @@ -1463,6 +1463,29 @@ int xhci_endpoint_init(struct xhci_hcd *xhci, > } > } > > + /* > + * Check for undercalculated bandwidth quirk for interrupt endpoints > + * associated with fullspeed BI. > + */ > + if ((xhci->quirks & XHCI_LIMIT_FS_BI_INTR_EP) && > + usb_endpoint_xfer_int(&ep->desc) && > + udev->speed == USB_SPEED_FULL && > + interval == 5) { > + struct usb_device *top_dev; > + > + for (top_dev = udev; > + top_dev->parent && top_dev->parent->parent; > + top_dev = top_dev->parent) > + /* Found device below root hub */; > + > + /* > + * If the top device is operating at fullspeed, then the > + * controller is using fullspeed BI for this device. > + */ > + if (top_dev->speed == USB_SPEED_FULL) > + interval = 4; > + } > + If we write a new xhci-snps driver then adjusting the interval could be done in the .add_endpoint override, after calling xhci_add_endpoint() If not then something like this should work. Maybe turn it into a separate function for readability. xhci_tune_interval_quirk(xhci, udev, ep, &interval) -Mathias
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index 1053b43008e4..e01d0ddb012a 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -1463,6 +1463,29 @@ int xhci_endpoint_init(struct xhci_hcd *xhci, } } + /* + * Check for undercalculated bandwidth quirk for interrupt endpoints + * associated with fullspeed BI. + */ + if ((xhci->quirks & XHCI_LIMIT_FS_BI_INTR_EP) && + usb_endpoint_xfer_int(&ep->desc) && + udev->speed == USB_SPEED_FULL && + interval == 5) { + struct usb_device *top_dev; + + for (top_dev = udev; + top_dev->parent && top_dev->parent->parent; + top_dev = top_dev->parent) + /* Found device below root hub */; + + /* + * If the top device is operating at fullspeed, then the + * controller is using fullspeed BI for this device. + */ + if (top_dev->speed == USB_SPEED_FULL) + interval = 4; + } + mult = xhci_get_endpoint_mult(udev, ep); max_packet = usb_endpoint_maxp(&ep->desc); max_burst = xhci_get_endpoint_max_burst(udev, ep); diff --git a/include/linux/usb/xhci-quirks.h b/include/linux/usb/xhci-quirks.h index 65bb62d3d31d..5bedf5a25f7a 100644 --- a/include/linux/usb/xhci-quirks.h +++ b/include/linux/usb/xhci-quirks.h @@ -59,5 +59,6 @@ #define XHCI_SG_TRB_CACHE_SIZE_QUIRK BIT_ULL(39) #define XHCI_NO_SOFT_RETRY BIT_ULL(40) #define XHCI_ISOC_BLOCKED_DISCONNECT BIT_ULL(41) +#define XHCI_LIMIT_FS_BI_INTR_EP BIT_ULL(42) #endif /* __LINUX_USB_XHCI_QUIRKS_H */
DWC_usb31 host version 1.90a and prior undercalculates the bandwidth available for interrupt endpoints. The controller will return bandwidth error on config endpoint commands if there are already 6 or more fullspeed interrupt endpoints with bInterval of 4 (or 4ms) associated with a single fullspeed bus instance (BI). To workaround this, configure and use the endpoint at a shorter interrupt interval. Lower the ep_ctx interval from 5 to 4 (or 2ms) for interrupt endpoints of the fullspeed BI. Note: we have not observed functional impact to the fullspeed devices by lowering the interrupt service interval (at least for a few devices that we tested). To simplify the workaround, let's just check and apply the workaround if the endpoint is a fullspeed interrupt endpoint with interval of 4ms and if the top parent device is also operating in fullspeed (i.e. associated with fullspeed BI). Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> --- Changes in v2: - None Note: Checkpatch will give a warning below for getting top_dev: WARNING: suspect code indent for conditional statements Since this logic is done everywhere else in the driver, I'm keeping it consistent here. drivers/usb/host/xhci-mem.c | 23 +++++++++++++++++++++++ include/linux/usb/xhci-quirks.h | 1 + 2 files changed, 24 insertions(+)