Hi Mark > > > +static void m_ioreadq(void __iomem *addr, void *buf, int len) { > > + u64 tmp_buf; > > + > > + while (len) { > > + tmp_buf = readq(addr); > > + memcpy(buf, &tmp_buf, len > 8 ? 8 : len); > > + len = len > 8 ? len - 8 : 0; > > + buf += 8; > > + } > > +} > > Wouldn't it be more efficient and readable to only do the memcpy() for the > trailing bytes and just do this memcpy() for the final word? The whole problem is with SDMA end - addr in that case. If code will try to Read it in non 64b mode, all remaining bits, will be lost. For example - doing 1B read on that register, will return 1B, but SDMA will transfer 8B, dropping remaining 7B. I have tried memcpy approach, and it was not stable. Regards Witek