Messages in this thread |  | | From | Daniel Palmer <> | Date | Wed, 10 Feb 2021 21:24:02 +0900 | Subject | Re: [PATCH 18/18] arm64: apple: Add initial Mac Mini 2020 (M1) devicetree |
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Hi Hector,
On Wed, 10 Feb 2021 at 20:49, Hector Martin <marcan@marcan.st> wrote:
> > Yeah, just don't use an imaginary dummy index for the reg. Use a real > > register offset from a clock controller instance base, and a register > > bit offset too if needed. > > I mean for fixed input clocks without any particular numbering, or for > temporary fake clocks while we figure out the clock controller. Once a > real clock controller is involved, if there are hardware indexes > involved that are consistent then of course I'll use those in some way > that makes sense.
This exact problem exists for MStar/SigmaStar too. As it stands there is no documentation to show what the actual clock tree looks like so everything is guess and I need to come up with numbers. I'm interested to see what the solution to this is as it will come up again when mainlining chips without documentation.
> The purpose of the clock in this particular case is just to make the > uart driver work, since it wants to know its reference clock; there is > work to be done here to figure out the real clock tree
FWIW arm/boot/dts/mstar-v7.dtsi has the same issue: Needs uart, has no uart clock. In that instance the uart clock setup by u-boot is passed to the uart driver as a property instead of creating a fake clock.
Cheers,
Daniel
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