On Sun, 2006-04-30 at 23:07 -0700, David S. Miller wrote: > From: "Michael Chan" <[EMAIL PROTECTED]> > Date: Sun, 30 Apr 2006 22:05:40 -0700 > > > Reading back the data register is a safe thing to do. This > > guarantees that the data is written before we change the address > > register to the zero value. Without the read, there is a danger of > > the value being written to SRAM address 0 instead of the desired > > address. > > Writes can be posted, but they cannot be reordered can they? >
Right, reordering is not allowed unless the relaxed ordering attribute is set. The read back here is not to guarantee ordering. Those SRAM address and data registers require "set-up" times for the SRAM writes and reads to work correctly. The "set-up" times are met either with config. cycles or with a read when using MMIO cycles. No udelays are needed, just a read will do. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
