Re: [PATCH V3] i2c: designware: fix wrong tx/rx fifo for ACPI

[Mika Westerberg]

On Mon, Dec 12, 2016 at 09:02:53PM +0200, Andy Shevchenko wrote:
> > +	tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> > +	rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> > +	if (!dev->tx_fifo_depth) {
> > +		dev->tx_fifo_depth = tx_fifo_depth;
> > +		dev->rx_fifo_depth = rx_fifo_depth;
> > +	} else if (tx_fifo_depth) {
> > +		dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
> > +				tx_fifo_depth);
> > +		dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
> > +				rx_fifo_depth);
> > +	}
> 
> So, let's clarify here:
> Is it possible to have an IP without parameter block enabled? I mean to
> read something arbitrary (or zeroes, or all-ones) from param1.

Yes and it is Intel IP. Haswell IIRC and it returned zeroes.