[PATCH] i2c-mpc: work around missing-9th-clock-pulse bug

[Grant Likely]

On 7/10/07, Domen Puncer <domen.puncer at telargo.com> wrote:
> On 10/07/07 14:40 +0200, Jean Delvare wrote:
> > Hi Grant, hi Domen,
> >
> > On Tue, 10 Jul 2007 00:22:05 -0600, Grant Likely wrote:
> > > On 7/10/07, Domen Puncer <domen.puncer at telargo.com> wrote:
> > > > Work around a problem reported on:
> > > > http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html
> > > > Without this patch I2C on mpc5200 becomes unusable after a while.
> > > > Tested on mpc5200 boards by Matthias and me.
> > > >
> > > >
> > > > Signed-off-by: Domen Puncer <domen.puncer at telargo.com>
> > >
> > > Looks good to me,
> > >
> > > Acked-by: Grant Likely <grant.likely at secretlab.ca>
> >
> > OK, I will take this patch, but I'd like you to add a comment before
> > mpc_i2c_fixup() explaining what exactly the problem is and how it is
> > worked around. Otherwise it's a bit obscure what is going on.
>
> OK.
>
> >
> > I guess you want this patch in 2.6.23-rc1?
>
> Yes.
>
> So... v3:
> <----------- cut ------------->
>
> Work around a problem reported on:
> http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html
> Without this patch I2C on mpc5200 becomes unusable after a while.
> Tested on mpc5200 boards by Matthias Fechner and me.
>
>
> Signed-off-by: Domen Puncer <domen.puncer at telargo.com>
>
> ---
>  drivers/i2c/busses/i2c-mpc.c |   21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> Index: work-powerpc.git/drivers/i2c/busses/i2c-mpc.c
> ===================================================================
> --- work-powerpc.git.orig/drivers/i2c/busses/i2c-mpc.c
> +++ work-powerpc.git/drivers/i2c/busses/i2c-mpc.c
> @@ -74,6 +74,24 @@ static irqreturn_t mpc_i2c_isr(int irq,
>         return IRQ_HANDLED;
>  }
>
> +/* Sometimes 9th clock pulse isn't generated, so slave doesn't release
> + * the bus.  Documented and suggested workaround on
> + * http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html
> + */

I don't think it's a great idea to use a link;  You should copy the
important parts into the .c file.  Archives may not be forever, and
links cannot be read when offline.  If the text is too long for the
middle of the C file; then put the documentation at the top right
after the header block.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely at secretlab.ca
(403) 399-0195