On Mon, Feb 04, 2019 at 12:17:43PM +0000, David Laight wrote: > From: Jarkko Sakkinen > > Sent: 01 February 2019 11:20 > > The current approach to read first 6 bytes from the response and then tail > > of the response, can cause the 2nd memcpy_fromio() to do an unaligned read > > (e.g. read 32-bit word from address aligned to a 16-bits), depending on how > > memcpy_fromio() is implemented. If this happens, the read will fail and the > > memory controller will fill the read with 1's. > > To my mind memcpy_to/fromio() should only be used on IO addresses that are > adequately like memory, and should be implemented in a way that that won't > generate invalid bus cycles. > Also memcpy_fromio() should also be allowed to do 'aligned' accesses that > go beyond the ends of the required memory area. > > ... > > > > - memcpy_fromio(buf, priv->rsp, 6); > > + memcpy_fromio(buf, priv->rsp, 8); > > expected = be32_to_cpup((__be32 *) &buf[2]); > > - if (expected > count || expected < 6) > > + if (expected > count || expected < 8) > > return -EIO; > > > > - memcpy_fromio(&buf[6], &priv->rsp[6], expected - 6); > > + memcpy_fromio(&buf[8], &priv->rsp[8], expected - 8); > > Why not just use readl() or readq() ? > > Bound to generate better code. For the first read can be done. The second read is of variable length. /Jarkko
