On Tue, Nov 17, 2009 at 11:22:11PM +0300, Anton Vorontsov wrote: > 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. :-(
Oh. On the other hand, we can postpone the gpio_direction_output() call, and still require that the platform code (or firmware) should be responsible for setting a sane default values on the chip selects. -- Anton Vorontsov email: cbouatmai...@gmail.com irc://irc.freenode.net/bd2 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
