[spi-devel-general] [PATCH v3 0/2] spi: driver for Cirrus EP93xx SPI controller

[Mika Westerberg]

On Fri, Apr 16, 2010 at 01:28:05PM -0500, H Hartley Sweeten wrote:
> 
> I finally was able to get this working on my system.  Not sure what the issue
> was earlier.

Great :)

> The only thing I don't like right off hand is the chip select handling.
> 
> The way it currently is done you are limited to using only the built-in GPIO's
> of the EP93xx.  This prohibits a system from using an external i2c/spi/etc.
> gpio expander to provide more chip selects.  And if a platform is not setup
> correctly, the BUG_ON in cs_to_gpio in your example for the tx72xx is pretty
> nasty.

Yes the example was just a hack.

However, I'm not sure what you mean by limited only to built-in GPIOs? Currently
the driver does:

        info->cs_control(spi->chip_select, value, info->data);

when it wants to assert/deassert the chip select. I don't see how this is
limited to built-in GPIOs only (maybe I'm missing something). Now it is in
responsibility of platform board files to allocate necessary chipselect lines,
and translate 'spi->chip_select' and 'value' to something meaningful.

> Ryan and I worked out a runtime setup/cleanup for the spi device chip selects
> in the spi driver I have in my tree.  I will take a look at it and see how
> much trouble it will be to implement in your driver.

Ok.

> Anyway, now that I have your driver functioning I will be able to actually
> provide some feedback to you.

That sounds good.

Thanks,
MW