Cypress ISD-300A

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A few days ago, I asked the best way to connect an IDE disk to an ARM
running Linux.

Now, I'm considering using a Cypress ISD-300A "USB-to-ATA" converter,
connecting it to one of the USB device ports on the ARM (AT91RM9200).  I see
some level of driver support for using the Cypress under Linux, but now I'd
like to get any feedback I can from any developers who have gone this route.

Is this a reasonable way to connect a CD-ROM and HD to an embedded ARM Linux


Re: Cypress ISD-300A
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Is there a really good reason for this? Sounds like you are inheriting
lowered performance and annoying complexity vs. simply attaching the IDE
device directly to GPIOs or the uP's main address space.

Re: Cypress ISD-300A
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I am not sure if my reason is good.  Your suggestion was my first approach,
but attaching the IDE port to GPIO pins or mapping it into memory space does
not seem to land very squarely on top of the Linux mainstream.  While the
ISD-300A is not exactly mainstream either, it is supported, including the
faster IDE modes.

Re: Cypress ISD-300A
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Hmm. Well, I don't know that *any* embedded system can truly be said to
"land squarely on top of the Linux mainstream". On general principle, I'd be
very very reluctant to add USB into the equation unless there was a damn
good reason for it - and the only reason that qualifies (to me) is "Must be
able to attach general-purpose USB peripherals".

It's not uncommon for ARM-based systems to implement IDE interfaces on
GPIOs. I've got one board on my desk that uses a regular PC super I/O chip,
but that's rather a maverick. Look at some of the arm-linux branches, I'm
*sure* you must be able to find some extant code to handle this, at least
for PXA25x-based and SA1110-based systems. Sure, some porting will be needed
to your Atmel chip, but it shouldn't be difficult.

Re: Cypress ISD-300A

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Thanks.  Since the Atmel chip has 2 USB host ports with Linux support, my
thought was to lay down traces to connect it directly to the ISD-300A, with
no cable or connectors.  The advantage (so my thinking went) was that I
would get reasonable performance (UDMA, 480mbit transfer rate) with minimal
processor involvement (DMA) and minimal kernel hacking.  The though of using
something as complicated as USB for this does bother me.

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I assume the board on your desk is an ARM with PCI?  I'd actually like to
look up this board, if it's a commercially supported "development" product.


Re: Cypress ISD-300A
Hi Ian,

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I admit I'm prejudiced against USB, but I just wouldn't do things this way.

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I actually tried to sell it recently, you want to buy it? :) It's a SA1110
board with PCI. Actually it is the EVB for the ITE IT8152 PCI bridge. It's
not commercially supported any more because the SA1110 is discontinued.

Even if you don't want the board, I'm happy to make you a copy of the Linux
CD-ROM released for it, maybe it will give you some insights.

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