Subject: [PATCH v2 2/2] i2c: New bus driver for the QUP I2C controller

From: [email-masked] (Bjorn Andersson)
Date: Fri, 17 Jan 2014 14:19:39 -0800

On Thu 16 Jan 16:33 PST 2014, Stephen Boyd wrote:

> On 01/16, Bjorn Andersson wrote:
> > On Wed 15 Jan 08:46 PST 2014, Stephen Boyd wrote:
> > 
> > > On 01/13, Bjorn Andersson wrote:
> > > > +
> > > > +static int
> > > > +qup_i2c_poll_state(struct qup_i2c_dev *qup, u32 req_state, bool only_valid)
> > > > +{
> > > > +	int retries = 0;
> > > > +	u32 state;
> > > > +
> > > > +	do {
> > > > +		state = readl(qup->base + QUP_STATE);
> > > > +
> > > > +		/*
> > > > +		 * If only valid bit needs to be checked, requested state is
> > > > +		 * 'don't care'
> > > > +		 */
> > > 
> > > It looks like req_state == 0 means only_valid == true. Can we
> > > drop the only_valid argument to this function?
> > > 
> > 
> > In all cases but the reset in the beginning of qup_i2c_xfer, so it seems that
> > it has to stay.
> 
> Oh that's because QUP_RESET_STATE is equal to 0? It looks like
> bits 0 and 1 are the state field and bit 2 is a flag indicating
> that bits 0 and 1 are valid. Why not OR in the QUP_STATE_VALID
> flag into the macros that are passed to this function? Then the
> logic would simply be looping looking for a match of the
> req_state (which is really a mask now).

While it's true that req_state == 0 means only_valid, it is not true that
only_valid means req_state == 0. So there would be no way to differentiate
between "valid and reset" and "valid and don't care about run/pause/reset".

So I could move the logic around, but I don't see how we could reduce the
number of parameters to the function.

// Bjorn