Re: [PATCH v2 1/4] i2c: sunxi: Add Reduced Serial Bus (RSB) support

From: Maxime Ripard
Date: Thu Mar 05 2015 - 17:10:12 EST


On Thu, Mar 05, 2015 at 07:40:44PM +0100, Wolfram Sang wrote:
>
> > > I don't have the bandwidth for a full review right now. However, I
> > > already wanted to tell you guys that my gut feeling is that this
> > > protocol is quite far away from I2C. P2WI was already at the edge.
> > > Maybe there is a better place for such custom stuff? I dunno yet.
> >
> > That's unfortunate, especially since it looks closer to SPI than what
> > P2WI even was.
>
> SPI? I assume you mean I2C. Can you elaborate your reasoning?

Yeah, I obviously meant I2C, sorry.

P2WI had no address. It was a single-device bus. However, the way it
communicated with the device was very close to I2C, apart from a
parity bit instead of the ACK.

From that regard, RSB is a multiple device bus, using addresses, just
like I2C. The way it communicates is basically the one used by P2WI.

So really, it just is more I2C-alike than P2WI has ever been.

> > What would be your suggestion?
>
> Let me quote:
>
> "I don't have the bandwidth for a full review right now... I dunno
> yet."

Good thing that we are not talking about a full review then, but more
a philosophical discussion.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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