> timur.t...@gmail.com wrote on 09/09/2009 16:24:15:
> >
> > On Wed, Sep 9, 2009 at 4:19 AM, Joakim
> > Tjernlund<joakim.tjernl...@transmode.se> wrote:
> > >
> > > I wonder if this hides another problem too.
> > > if the timeout hits, -1 is returned.
> > >
> > > Then in i2c_read()/i2c_write() you have:
> > > if (i2c_wait4bus() >= 0
> > > && i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
> > > && __i2c_write(&a[4 - alen], alen) == alen)
> > > i = 0; /* No error so far */
> > > notice how the latter part, i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
> > > && __i2c_write(&a[4 - alen], alen) == alen)
> > > is ignored(never called) when i2c_wait4bus() returns -1
> >
> > Yeah, that is a bit odd. It looks like it was supposed to be some
> > short-cut way to avoid multiple if-then-else clauses.
> >
> > I wouldn't say my patch is *hiding* another problem -- that code looks
> > broken either way.
>
> Yes, bad wording on my part.
>
> >
> > Someone should probably fix it to look like this:
> >
> > if (i2c_wait4bus() < 0)
> > return -1;
>
> I suspect that this won't work in the long run. If
> i2c_wait4bus() times out, the bus is likely stuck and will
> never recover. Probably best to ignore these errors and reset the controller
> and try again or something ..
>
> >
> > if (!i2c_write_addr(dev, I2C_WRITE_BIT, 0))
> > return -1;
> >
> > if (__i2c_write(&a[4 - alen], alen) != alen)
> > return -1;
> >
> > and so on.
> > i = 0; /* No error so far */
> >
> > --
> > Timur Tabi
> > Linux kernel developer at Freescale
> >
BTW, the fdr and dfsr calculations appears totally bogus. It seems
like the table is taken from some examples in AN2919 and it is pure luck
that it works most of the time. For me it does not work 100%, instead I get
random errors which hangs both the controller and the RTC device.
Jocke
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