On 27.1.2025 14.06, Raju Rangoju wrote:
During the High-Speed Isochronous Audio transfers, xHCI
controller on certain AMD platforms experiences momentary data
loss. This results in Missed Service Errors (MSE) being
generated by the xHCI.
The root cause of the MSE is attributed to the ISOC OUT endpoint
being omitted from scheduling. This can happen either when an IN
endpoint with a 64ms service interval is pre-scheduled prior to
the ISOC OUT endpoint or when the interval of the ISOC OUT
endpoint is shorter than that of the IN endpoint. Consequently,
the OUT service is neglected when an IN endpoint with a service
interval exceeding 32ms is scheduled concurrently (every 64ms in
this scenario).
This issue is particularly seen on certain older AMD platforms.
To mitigate this problem, it is recommended to adjust the service
interval of the IN endpoint to not exceed 32ms (interval 8). This
adjustment ensures that the OUT endpoint will not be bypassed,
even if a smaller interval value is utilized.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Raju Rangoju <Raju.Rangoju@xxxxxxx>
---
Changes since v3:
- Bump up the enum number XHCI_LIMIT_ENDPOINT_INTERVAL_9
Changes since v2:
- added stable tag to backport to all stable kernels
Changes since v1:
- replaced hex values with pci device names
- corrected the commit message
drivers/usb/host/xhci-mem.c | 5 +++++
drivers/usb/host/xhci-pci.c | 25 +++++++++++++++++++++++++
drivers/usb/host/xhci.h | 1 +
3 files changed, 31 insertions(+)
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 92703efda1f7..d3182ba98788 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1420,6 +1420,11 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
/* Periodic endpoint bInterval limit quirk */
if (usb_endpoint_xfer_int(&ep->desc) ||
usb_endpoint_xfer_isoc(&ep->desc)) {
+ if ((xhci->quirks & XHCI_LIMIT_ENDPOINT_INTERVAL_9) &&
+ usb_endpoint_xfer_int(&ep->desc) &&
+ interval >= 9) {
+ interval = 8;
Commit message describes this as an issue triggered by High-Speed Isoc In
endpoints that have interval larger than 32ms.
This code limits interval to 32ms for Interrupt endpoints (any speed),
should it be isoc instead?
Are Full-/Low-speed devices really also affected?
Thanks
Mathias
