Re: [PATCH 1/4] dmaengine: dw_dmac: use helper macromodule_platform_driver()

[Felipe Balbi]

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@xxxxxxxxxx> wrote:
> > On Wed, Oct 10, 2012 at 2:34 PM, Andy Shevchenko
> > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> >> On Tue, 2012-10-02 at 14:41 +0300, Andy Shevchenko wrote:
> >>> From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> >>>
> >>> 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.

-- 
balbi

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