Re: [PATCH] i2c: mxs: Rework the PIO mode operation

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Hi Lucas,

> Hi Marek,
> 
> Am Montag, den 15.07.2013, 04:05 +0200 schrieb Marek Vasut:
> > Hi,
> > 
> > > Analyze and rework the PIO mode operation. The PIO mode operation
> > > was unreliable on MX28, by analyzing the bus with LA, the checks
> > > for when data were available or were to be sent were wrong.
> > > 
> > > The PIO WRITE has to be completely reworked as it multiple problems.
> > > The MX23 datasheet helped here, see comments in the code for details.
> > > The problems boil down to:
> > > - RUN bit in CTRL0 must be set after DATA register was written
> > > - The PIO transfer must be 4 bytes long tops, otherwise use
> > > 
> > >   clock stretching.
> > > 
> > > Both of these fixes are implemented.
> > > 
> > > The PIO READ operation can only be done for up to four bytes as
> > > we are unable to read out the data from the DATA register fast
> > > enough.
> > > 
> > > This patch also tries to document the investigation within the
> > > code.
> > > 
> > > Signed-off-by: Marek Vasut <marex@xxxxxxx>
> > > Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> > > Cc: Fabio Estevam <r49496@xxxxxxxxxxxxx>
> > > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> > > Cc: Shawn Guo <shawn.guo@xxxxxxxxxx>
> > > Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> > > Cc: <to-fleischer@xxxxxxxxxxx>
> > 
> > I so far got confirmation from ALexandre this patch works. Can someone
> > else test it please? I'd like to roll out a final version to close this
> > issue.
> 
> Sorry, I wasn't able to test it until now. I now have the respective
> hardware at my desk again, so I'll get you a report by latest day after
> tomorrow.

Thanks

> I'll post some comments to the patch itself in the meantime.

Consider the patch RFC, I know there are about two unused functions and maybe 
some compiler warnings.

Best regards,
Marek Vasut
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