Hi Wolfram,
On Tue, 20 Jun 2017 19:28:10 +0200, Wolfram Sang wrote:
> Hi Jean,
>
> > > + bool did_stop = false;
> >
> > I'm pretty certain you want to declare and initialize this variable
> > outside the loop.
>
> Why? Well, it doesn't matter anymore but what is wrong with limiting the
> variable like this?
There's no problem with the scope. The problem is with the
initialization. The way you did, did_stop gets reset to false with
every iteration, which isn't what you want.
> > (...)
> > 1* Repeated start happens between messages of a same transaction, and
> > you handle that case above. However in the case of 10-bit address
> > clients, there is also a repeated start happening during the address
> > phase of the transaction, if the first message is a read. Did you check
> > what the SCCB protocol expects in that case?
>
> SCCB defines addresses to be 7 bit.
I looked at how 10-bit addressing works again and in fact it is simply
impossible to not use repeated start when reading from a 10-bit address
slave. Only the first 2 bits of the 10-bit address are repeated in the
read part of the transaction. If there was a stop between the two parts
then there would be no way to know which 10-bit slave should send the
data.
> > (...)
> > --- linux-4.11.orig/drivers/i2c/algos/i2c-algo-bit.c 2017-06-19 09:57:17.949074198 +0200
> > +++ linux-4.11/drivers/i2c/algos/i2c-algo-bit.c 2017-06-19 10:23:26.711088536 +0200
> > @@ -553,8 +553,17 @@ static int bit_xfer(struct i2c_adapter *
> > nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
> > if (!(pmsg->flags & I2C_M_NOSTART)) {
> > if (i) {
> > - bit_dbg(3, &i2c_adap->dev, "emitting "
> > - "repeated start condition\n");
> > + if (msgs[i - 1].flags & I2C_M_STOP) {
> > + bit_dbg(3, &i2c_adap->dev,
> > + "emitting enforced stop condition\n");
> > + i2c_stop(adap);
> > + bit_dbg(3, &i2c_adap->dev,
> > + "emitting start condition\n");
> > + i2c_start(adap);
> > + }
>
> else
Oops. Right, fixed, thanks.
>
> > +
> > + bit_dbg(3, &i2c_adap->dev,
> > + "emitting repeated start condition\n");
> > i2c_repstart(adap);
> > }
> > ret = bit_doAddress(i2c_adap, pmsg);
>
> A lot better! I like it very much. And also
>
> Tested-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
>
> Do you want to cook up a patch or shall I? I'd just need a SoB then.
I'll send a proper patch shortly.
> Thanks for the improvement!
You're welcome.
--
Jean Delvare
SUSE L3 Support
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