[PATCH v7 1/2] spi: implemented driver for Cirrus EP93xx SPI controller

[Mika Westerberg]

On Sun, May 09, 2010 at 05:47:34PM +0100, Martin Guy wrote:
> On 5/9/10, Mika Westerberg <mika.westerberg at iki.fi> wrote:
> > On Sat, May 08, 2010 at 06:32:47PM +0100, Martin Guy wrote:
> >  > On 5/6/10, Mika Westerberg <mika.westerberg at iki.fi> wrote:
> >  > > This patch adds an SPI master driver for the Cirrus EP93xx SPI controller found
> >  > >  in EP93xx chips.
> >
> > >    I'm confused by the change in this version of the structure of the
> >  > board setup code.
> >
> >  For Sim.One, I modified your patches a bit and resulting patch is
> >  included. Note that I have hooked EGPIO9 as a chip select but in
> >  normal case (SFRMOUT) you can just do following (leave .controller_data
> >  as NULL):
> 
> Many thanks. If you want to submit this to mainline there are just a
> couple of changes to make:
> 
> > +#define MMC_CHIP_SELECT_GPIO EP93XX_GPIO_LINE_EGPIO9
> 
> EGPIO9 is part of the keyboard controller - I don't think we can
> hijack that for a patch to the mainline kernel! I've used EGPIO15
> which is unused and on TP17 just south of the CPU.

It was just my own hack ;) Maybe I also use EGPIO15 for the chip select.

I think that we can submit this to mainline only after next Sim.One
revision (is there going to be next one?) where we know what that
GPIO line will be.

> >                 .mode                   = SPI_MODE_0,
> 
> Using SPI_MODE_3 increases the read speed from 319 kB/s to 367 kB/s -
> even when using a GPIO as the chip select.

OK. So we will use MODE_3 in Sim.One (and maybe in TS-7260). Thanks.

> Your 4GB card fix works here too, though I'm seeing no difference in
> anything between using SFRMOUT and a GPIO for the chip select. Did you
> see any functionality or performance improvements using a GPIO for CS
> with the SD cards you are testing?

Actually no. But at least chipselect should work better so I guess
it could help with cards that haven't previously worked.

That 4GB hack is something that need to be further investigated;
It shows that some SDHC cards (at least) will fail when reading
last (Linux) block using multiblock read.

Regards,
MW