On Wed, Oct 10, 2012 at 04:42:00PM +0300, Felipe Balbi wrote: > Hi, > > On Wed, Oct 10, 2012 at 03:52:40PM +0300, Andy Shevchenko wrote: > > On Wed, Oct 10, 2012 at 3:40 PM, Felipe Balbi <ba...@ti.com> wrote: > > > On Wed, Oct 10, 2012 at 12:21:04PM +0300, Andy Shevchenko wrote: > > >> On Wed, Oct 10, 2012 at 12:08 PM, viresh kumar <viresh.ku...@linaro.org> > > >> wrote: > > >> > On Wed, Oct 10, 2012 at 2:34 PM, Andy Shevchenko > > >> > <andriy.shevche...@linux.intel.com> wrote: > > >> >> On Tue, 2012-10-02 at 14:41 +0300, Andy Shevchenko wrote: > > >> >>> From: Heikki Krogerus <heikki.kroge...@linux.intel.com> > > >> >>> > > >> >>> Since v3.2 we have nice macro to define the platform driver's init > > >> >>> and exit > > >> >>> calls. This patch simplifies the dw_dmac driver by using that macro. > > >> >> > > >> >> Actually we can't do this. It will break initialization of some other > > >> >> drivers. > > >> > > > >> > why? > > >> > > >> We have spi, i2c and hsuart devices connected to the DMA controller. > > >> In case we would like to use DMA we have to have the dw_dmac loaded > > >> before them. Currently we have spi driver on subsys_initcall level, > > >> and Mika, who is developing it, will change to module_init_call level. > > >> However, it will just hide the potential issue. He also tried to use > > >> deferred module loading, but we don't know if it's good solution or > > >> not, and that solution requires something to stop deferring at some > > >> moment. > > >> > > >> Might be we missed something and there is a better solution. > > > > > > if they can only work with DMA, they should return -EPROBE_DEFER so > > > their probe() function can be called after DMA driver has finished > > > probing. > > > > They could work either with DMA or via PIO mode. > > How does the driver know when to stop to return -EPROBE_DEFER? > > Why would you even allow to work as PIO-only ? Who would even want to > use the driver as PIO only ?
Think about SPI or I2C, if we don't have DMA available we are still able to use the driver (and the bus) instead of just failing. > In any case, you can add a Kconfig choice like WHATEVER_PIO_ONLY and > only return -EPROBE_DEFER ifndef WHATEVER_PIO_ONLY. Why would we add more Kconfig options for things that can be checked runtime? Distro makers need to select that option anyway so it doesn't gain anything, except confuses users. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/