TD_MASK
head = hc32_to_cpu(ohci, READ_ONCE(ed->hwHeadP)) & TD_MASK;
td_dma &= TD_MASK;
head = hc32_to_cpu(ohci, ed->hwHeadP) & TD_MASK;
savebits = *prev & ~cpu_to_hc32 (ohci, TD_MASK);