Re: [PATCH 3/8] i2c: omap: fix error checking

Felipe Balbi
2012-10-25T10:10:10Z

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Hi,

On Wed, Oct 24, 2012 at 04:41:11PM +0200, Michael Trimarchi wrote:
> Hi
>
> On 10/22/2012 11:46 AM, Felipe Balbi wrote:
> > It's impossible to have Arbitration Lost,
> > Read Overflow, and Tranmist Underflow all
> > asserted at the same time.
> >
> > Those error conditions are mutually exclusive
> > so what the code should be doing, instead, is
> > check each error flag separataly.
> >
> > Signed-off-by: Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>
> > ---
> > drivers/i2c/busses/i2c-omap.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> > index bea0277..e0eab38 100644
> > --- a/drivers/i2c/busses/i2c-omap.c
> > +++ b/drivers/i2c/busses/i2c-omap.c
> > @@ -587,9 +587,9 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
> > goto err_i2c_init;
> > }
> >
> > - /* We have an error */
> > - if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR |
> > - OMAP_I2C_STAT_XUDF)) {
> > + if ((dev->cmd_err & OMAP_I2C_STAT_AL)
> > + || (dev->cmd_err & OMAP_I2C_STAT_ROVR)
> > + || (dev->cmd_err & OMAP_I2C_STAT_XUDF)) {
>
> Sorry, what is the difference? I didn't understand the optimisation
> and why now is more clear. Can you just add a comment?

semantically they're not the same, right ? We want to check if each of
those bits are set, not if all of them are set together.

my 2 cents.

--
balbi

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