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Re: [ts-7000] Re: SPI kernel driver sample code?

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Subject: Re: [ts-7000] Re: SPI kernel driver sample code?
From: Mika Westerberg <>
Date: Mon, 6 Sep 2010 19:34:10 +0300
On Mon, Sep 06, 2010 at 02:55:48PM -0000, Blair wrote:
> No, I'm using the /dev/mem peek/poke method for the moment.  Kris at TS said 
> they messed with the ep93xx_spi driver a while back and "found that the 
> kernel routines for this are rather inefficient, e.g. the SPI controller is 
> reset before every transaction, and the tempsensor application we have 
> written will directly access the hardware.  This means you can intelligently 
> stream data out of the SPI core faster than you would with the kernel 
> interface."

I'm assuming that we are talking about the ep93xx_spi driver that
is in the mainline kernel, right? I'm pretty sure that it doesn't
reset the SPI controller before every transaction. We've been using
that to interface SD/MMC-cards and it can transfer something like
370kB/s.

It is hard to believe that doing such in userspace would be faster,
since you have to poll (no interrupts/DMA available).

MW


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