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

[Ryan Chen]

> Subject: Re: [PATCH v28 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and enable-dma properties
> 
> 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?
Yes, This is my intent to do.
Disable I2C DMA entirely on AST2600.
If I remove DMA, should can I keep byte and buffer for sysfs?