On Thu, 2013-07-04 at 15:25 -0700, Mike Turquette wrote: > Quoting Luciano Coelho (2013-07-04 14:05:12) > > Add a flag that indicate whether the clock is a crystal or not. Since > > no clocks set this flag right now, include an additional flag that > > indicates whether the type is set or not. If the CLK_IS_TYPE_DEFINED > > flag is not set, the value of the CLK_IS_TYPE_XTAL flag is undefined. > > This ensures backwards compatibility. > > > > Additionally, parse a new device tree binding in clk-fixed-rate to set > > this flag. > > > > Signed-off-by: Luciano Coelho <coe...@ti.com> > > --- > > > > I'm not familiar with the common clock framework and I'm not > > entirely sure the flags can be used in such a way, but to me it looks > > reasonable, since some clock consumers may need to know what type of > > clock is being provided. > > > > Specifically, the wl12xx firmware needs to know if the clock is XTAL > > or not to handle the stabilization and boosts properly. > > Hi Luciano,
Hi Mike, > I'd like clarification on one point. Is the same clock input signal used > on the wifi chip? What I mean is, are there multiple clock inputs and > XTAL is one, and not-XTAL is another? This wifi chip can work with a few different clocks and some of them are XTAL and others are not. What the chip's firmware can use is one of these: 19.2MHz (not XTAL) 26.0MHz (not XTAL) 26.0MHz (XTAL) 38.4MHz (not XTAL) 38.4MHz (XTAL) 52.0MHz (not XTAL) It treats the XTAL clocks differently (but I don't really understand enough of the details), so the driver needs to configure the firmware according to these values. > Or is it the same clock input and basically the problem is that you need > to know what kind of waveform to expect (e.g. square versus sine)? It's the same clock input in the chip's perspective. One clock input that can be any of the combinations I mentioned above. Again, I'm not familiar with clocks, so I guess the square vs. sine explanation is plausible. What I could see in the firmware is that it handles the clocks differently if they're xtal or not. -- Luca. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
