Re: [PATCH 1/3] i2c: mxs: always end a transfer with a proper STOP

[Lucas Stach <l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

Hi Wolfram,

Am Dienstag, den 09.04.2013, 10:32 +0200 schrieb Wolfram Sang:
> Hi,
> 
> > A restart transfer is when you just repeat the START condition, without
> > putting the device address on the bus again.
> 
> Well, never heard this term before. Where did you get it from?
> 
> > In the MXS driver we put the device address on the bus for every
> > transaction we get handed in from the i2c core, so there is never a
> > situation where we just repeat the start condition without sending out
> > the device address. Before this patch we would not match every
> > transaction, but only the last in the list of pending ones, with a STOP
> > condition, which is a violation of the spec.
> 
> I still don't get it. You can drop a STOP if you replace it with
> a repeated start. In fact, this is crucial in multi-master setups,
> otherwise another master could break into your transfer containing
> multilple messages. So, if MXS does the right thing on sending START
> (doing a correct start sequence), we should not send STOP. If it needs
> the STOP to create a correct START, then be it. But then, I'd wonder why
> it worked so far...
> 

Ok, I looked this up again and got a nice explanation by Uwe and it
seems I based this patch on a wrong interpretation of the spec on my
side. I'll resend without this one.

Regards,
Lucas

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