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Diffstat (limited to 'lib')
-rw-r--r--lib/libusb/libusb20.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/lib/libusb/libusb20.c b/lib/libusb/libusb20.c
index 2f4ee780cabc..91ed9d797afd 100644
--- a/lib/libusb/libusb20.c
+++ b/lib/libusb/libusb20.c
@@ -176,6 +176,12 @@ libusb20_tr_open_stream(struct libusb20_transfer *xfer, uint32_t MaxBufSize,
return (LIBUSB20_ERROR_BUSY);
if (MaxFrameCount & LIBUSB20_MAX_FRAME_PRE_SCALE) {
MaxFrameCount &= ~LIBUSB20_MAX_FRAME_PRE_SCALE;
+ /*
+ * The kernel can setup 8 times more frames when
+ * pre-scaling ISOCHRONOUS transfers. Make sure the
+ * length and pointer buffers are big enough:
+ */
+ MaxFrameCount *= 8;
pre_scale = 1;
} else {
pre_scale = 0;
@@ -200,8 +206,13 @@ libusb20_tr_open_stream(struct libusb20_transfer *xfer, uint32_t MaxBufSize,
}
memset(xfer->ppBuffer, 0, size);
- error = xfer->pdev->methods->tr_open(xfer, MaxBufSize,
- MaxFrameCount, ep_no, stream_id, pre_scale);
+ if (pre_scale) {
+ error = xfer->pdev->methods->tr_open(xfer, MaxBufSize,
+ MaxFrameCount / 8, ep_no, stream_id, 1);
+ } else {
+ error = xfer->pdev->methods->tr_open(xfer, MaxBufSize,
+ MaxFrameCount, ep_no, stream_id, 0);
+ }
if (error) {
free(xfer->ppBuffer);