Re: spi_mpc8xxx.c: chip select polarity problem

[Anton Vorontsov <cbouatmailru@gmail.com>]

On Tue, Nov 17, 2009 at 09:09:28PM +0100, Torsten Fleischer wrote:
> On Mon, Nov 16, 2009 at 19:00PM, Anton Vorontsov wrote:
> [...]
> > > So it might be better to fix up initial value in the platform code?
> > 
> > Oh, we actually cannot, because the driver calls
> > gpio_direction_output().
> > 
> > And since we don't know the mode prior to SPI device's driver
> > probe() finished, we'll have to set up an initial state in the
> > first SPI transfer. I.e. something like this:
> 
> In most cases the device drivers perform SPI transfers already in their 
> probe() function. How can it be ensured that the CS of all other devices are 
> inactive even if they are not initialized at that time?

Good question. Oh, well... then we have to use spi-cs-high,
no matter that it is a duplication of the 'compatible' property.
SPI bus drivers don't know all the devices and their CS level,
and so spi-cs-high is the only way to tell that information. :-(

-- 
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2