[LinuxBIOS] [PATCH] Remove Bitworks IMS

Richard Smith smithbone at gmail.com
Fri Nov 30 02:25:32 CET 2007

Carl-Daniel Hailfinger wrote:

>> If so I only need that for the initial boot.  After that I can issue
>> SPI read commands directly to the device.
> Which is a little bit slow/inefficient. I suspect that using a USB
> storage device (together with early USB initialization) will give you
> better overall performance.

Using multi-byte reads it should not be that much slower than the 
LPC->SPI read.  Perhaps a bit more overhead but not much.

Assuming the max SPI clock of 33Mhz I see in the data sheet is correct 
then, yes, the data rate will be much slower than USB.

That said, here in the OLPC offices we have still have periodic pain 
involved with USB booting.  A lot of usb sticks are just trash.  The 
generic case requires up to several seconds of delay before you can 
access them.

In anycase, I'll have to start with USB and I have to get the compressed 
fs image to fit in 15 megs or less or it won't matter.

Richard A. Smith
smithbone at gmail.com

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