Messages in this thread | | | Date | Wed, 10 Oct 2012 16:42:00 +0300 | From | Felipe Balbi <> | Subject | Re: [PATCH 1/4] dmaengine: dw_dmac: use helper macro module_platform_driver() |
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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 <balbi@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.kumar@linaro.org> wrote: > >> > On Wed, Oct 10, 2012 at 2:34 PM, Andy Shevchenko > >> > <andriy.shevchenko@linux.intel.com> wrote: > >> >> On Tue, 2012-10-02 at 14:41 +0300, Andy Shevchenko wrote: > >> >>> From: Heikki Krogerus <heikki.krogerus@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 ?
In any case, you can add a Kconfig choice like WHATEVER_PIO_ONLY and only return -EPROBE_DEFER ifndef WHATEVER_PIO_ONLY.
-- balbi [unhandled content-type:application/pgp-signature] | |