Re: [PATCH v28 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and enable-dma properties

[Jeremy Kerr]

Hi Ryan,

> > Sounds reasonable, but before you do so, how are you planning to manage the
> > allocation of DMA channels across multiple i2c peripherals?
> > 
> The AST2600 I2C hardware has only one can use DMA at a time.
> To avoid the complexity of managing DMA channel contention,
> I plan to use buffer mode by default for all controllers, which still provides
> better performance than byte mode without requiring DMA channel allocation.

OK, but your wording there ("by default") implies that DMA is still
selectable for one controller peripheral. In which case: you still have
the problem of managing DMA channel contention, but now it's at runtime
instead.

So my question still stands: how are you planning to enforce that DMA is
only enabled for one controller?

Or are you planning to disable I2C DMA entirely on AST2600?

Cheers,


Jeremy