Re: [PATCH 2/5] i2c: sh_mobile: add DMA support

[Wolfram Sang <wsa@the-dreams.de>]

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> > Note that the I2C drives uses subsys_initcall() for historic reasons,
> > while the DMA driver uses module_init(). This is hard to revert without
> > introducing potential regressions on older boards. So, the I2C DMA
> > support needs to handle deferred probe definately. I am with Laurent, I
> > don't see any other way, but I'd be glad to be enlightened...
> 
> While I believe that requesting the channel at transfer time is the good 
> solution, I think we should still try to move to module initcalls where 
> possible. The risk of regressions is real so proper testing is needed. My 
> question is, have you tried it ?

I would need to test all boards using this driver to not fail booting.
Usually I2C drivers are moved to subsys_initcall because they need
access to something critical (PMIC, GPIOs...) early. I don't see a sane
way to do that testing.

Other than that, even if we move to module_init, we reduce the chance of
getting a deferred probe, but we do not eliminate it...


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