Re: [RFC PATCH 01/16] Documentation: driver: add SoundWire BRA description

[Mark Brown <broonie@xxxxxxxxxx>]

On Tue, Aug 20, 2024 at 04:58:30PM +0200, Pierre-Louis Bossart wrote:
> On 8/20/24 13:53, Mark Brown wrote:

> > As far as the regmap core is concerned, yes - with SPI we do wind up
> > with ordering but that's because the SPI sync API is a thin wrapper
> > around the SPI async API rather than anything regmap does.

> ok. I am struggling a bit to adjust the plumbing that was obviously
> defined for SPI.

> The regmap async_write() doesn't have any wait, but there's a notifier
> that needs to be called by *something* that waits. I think the SPI layer
> has a set of kthreads but in our case we could just rely on a a
> workqueue after 1ms or something and do the wait then for the DMAs to
> complete and finally call the notifier to wake-up the regmap stuff.

From the regmap point of view the expectation is that when the caller
wants to know that all the I/Os have actually happened it should call
regmap_async_complete() which will do the actual blocking.  regmap
itself won't autonomously wait for anything, it's up to the caller to do
that (presumably it will at some point care).

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