On Tue, Nov 05, 2024 at 02:48:50PM +0530, 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 exceed 32ms (interval 8). This
Do you mean "not to exceed 32 ms"?
> 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>
> ---
> drivers/usb/host/xhci-mem.c | 5 +++++
> drivers/usb/host/xhci-pci.c | 14 ++++++++++++++
> drivers/usb/host/xhci.h | 1 +
> 3 files changed, 20 insertions(+)
>
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index d2900197a49e..4892bb9afa6e 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -1426,6 +1426,11 @@ 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;
> + }
This change ensures that the interval is <= 32 ms.
Alan Stern
