Re: [PATCH v1 RFC 1/2] spi: introduce fallback to pio

[Mark Brown]

On Mon, Jun 15, 2020 at 02:18:54PM +0000, Robin Gong wrote:
> On 2020/06/15 21:39 Mark Brown <broonie@xxxxxxxxxx> wrote:
> > On Mon, Jun 15, 2020 at 01:35:01PM +0000, Robin Gong wrote:

> > > Then how about choosing specific error code for such dma not ready
> > > case where nothing went out on the bus neither?

> > Yes, that's what I suggested.

> Seems not easy to find a suitable error value, how about EBADR which
> sounds like no any available dma_async_tx_descriptor got by calling dmaengine_prep_slave_sg? 

> #define EBADR           53      /* Invalid request descriptor */

We could also pass in a flag that could be set separately to the error
code to indicate that nothing had happened to the hardware yet.

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