Transfer rates with NAND

Hi,

I am wondering which NAND transfer rates are seen in embedded Linux projects. What to expect from the whole hardware/software subsystem?
I have one Geode LX design with CS5536 companion chip which by using built-in 8-bit Flash controller on PCI bus gives me slightly over 2MB/s. It's almost the same with Linux MTD driver and with a self-made basic driver. Is the speed here the matter of flash controller only? Which is the fastest flash controller out there? :)

thanks in advance,
Indrek

Hi Indrek,

the data transfer from the NAND to the CPU and viceversa depends on:

1. NAND bus maximum speed
2. CPU's bus controller speed (*) and its configuration
3. Read or Write operarations

The overhead added by the MTD layer or any other well written driver is irrelevant.

(*) I mean the bus that access the NAND which might not be the same bus that access the RAM

Enrico

The CS5536 NAND flash controller is fairly crap in terms of performance -- you don't get burst read/write transactions over PCI with it, so it goes very slowly as it has to do the whole PCI setup thing for every 4 bytes.

You'll get a maximum of something like 3 MiB/s from it IIRC. From a better controller and a decent chip you might get close to ten times that; at least in theory.

dwmw2