Messages in this thread | | | Date | Mon, 10 Nov 2014 15:02:15 -0800 | From | Sören Brinkmann <> | Subject | Re: [PATCH 1/2] arm: dts: zynq: Move crystal freq. to board level |
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On Tue, 2014-11-11 at 08:35AM +1000, Peter Crosthwaite wrote: > On Mon, Nov 10, 2014 at 7:34 AM, Sören Brinkmann > <soren.brinkmann@xilinx.com> wrote: > > On Sun, 2014-11-09 at 01:38PM +1000, Peter Crosthwaite wrote: > >> The fact that all supported boards use the same 33MHz crystal is a > >> co-incidence. The Zynq PS support a range of crystal freqs so the > >> hardcoded setting should be removed from the dtsi. Re-implement it > >> on the board level. > >> > >> This prepares support for Zynq boards with different crystal > >> frequencies (e.g. the Digilent ZYBO). > > > > Even with the 33MHz in the dtsi you can override it on the board-level. > > Just like the 'status' property is overriden in board dts files. > > > > Do you want the deletion undone? Even with override capability I think > it should be removed as the number is board level specific and the > dtsi should be limited to SoC level information.
I'm fine with it. Just wanted to point out that patch 2 does not strictly require this change and can stand on its own.
[...] > >> Im guessing long term this should be converted to a fixed clock. But > >> I think this at least steps in that direction. > > > > I was against that since it makes juggling with clock names more > > difficult. The problem is that the CCF uses a global name space of clock > > names. > > I thought it was just a > > clocks = < &phandle > > > Where's the namespacing issue? > > Btw I think the clocks=phandle would be populated the the dts as well. > So the DTSI would have no clocks = node, and the dts must populate it. > This allows support for an on-board off-soc clock controller > controlling the PS clock (which is in theory supported by the SoC).
Every call to clk_register needs to be passed in the clock's parent (unless it's a root clock). That parent is specified by its name. You won't see it as user/consumer, but when implementing a clock-provider. I think there is nothing preventing such a change, but it would make things more complicated for no good reason. Even if you have an off-chip clock controller, if that one doesn't provide a fixed clock input to Zynq, things are likely to break.
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