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

[Robin Gong]

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 */