On Mon, Nov 12, 2012 at 12:54:59, Igor Grinberg wrote: > On 11/12/12 08:38, Hiremath, Vaibhav wrote: > > On Sun, Nov 11, 2012 at 17:05:07, Igor Grinberg wrote: > >> > >> > >> On 11/08/12 20:34, Jon Hunter wrote: > >>> > >>> On 11/08/2012 12:17 PM, Paul Walmsley wrote: > >>>> On Thu, 8 Nov 2012, Jon Hunter wrote: > >>>> > >>>>> On 11/08/2012 11:58 AM, Paul Walmsley wrote: > >>>>>> On Thu, 8 Nov 2012, Jon Hunter wrote: > >>>>>> > >>>>>>> Igor was mentioning a h/w scenario where the 32kHz source is not > >>>>>>> present. However, I am not sure which devices support this and is > >>>>>>> applicable too. > >>>>>> > >>>>>> Pretty sure Igor is referring to the AM3517/3505. This is very poorly > >>>>>> documented, but can be observed in the AM3517 TRM Rev B (SPRUGR0B) Figure > >>>>>> 4-23 "PRM Clock Generator" and the AM3517 DM Rev C (SPRS550C) Section 4 > >>>>>> "Clock Specifications". > >>>>> > >>>>> But AFAICT, even in that h/w configuration the internal 32k > >>>>> oscillator will be used > >>>> > >>>> Just to clarify, there's no internal 32k oscillator used on the 3517/3505; > >>>> just a divider from the HF clock. > >>> > >>> Ah yes I see that now! > >>> > >>>>> and so the gptimer will still have a 32k clock source. > >>>> > >>>> That's a good question and you might want to check with Igor on that one, > >>>> the AM3517 TRM conflicts with the DM as to whether it's available to the > >>>> GPTIMER or not :-( > >>> > >>> Well the external 32k and internal divided down version go through the > >>> same mux and so that seems to imply either they are both available to > >>> the gptimer or neither is. > >> > >> Yep, but the /800 do not get you the 32768... > >> and that makes the timer suck. > >> Of course this can be dealt with in the clock subsystem > >> (I remember Paul said that he will look into that), but it will take time. > >> > >> Also, what about having the sys_clk instead of 32k for higher precision? > >> Is that possible already (without my patch)? > >> > > > > Yes, it is possible. You can choose it through bootargs. > > Is the kernel command line the only way for doing this? > I personally dislike it, because it brings multiple maintenance problems. > This must be possible at least through DT. > Its standard interface, so carries all the applicable pros and cons. I am not quite sure about runtime change of clocksoyrce, its pros and cons. Thanks, Vaibhav > > -- > Regards, > Igor. > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
