Re: [PATCH v2 1/5] dt-bindings: update device tree binding for Allwinner PRCM CCUs

[icenowy]

å 2017-03-27 21:47ïMaxime Ripard åéï
> On Mon, Mar 27, 2017 at 05:11:29PM +0800, Icenowy Zheng wrote:
> > 2017å3æ26æ 21:10ä Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>åéï
> > >
> > > On Thu, Mar 23, 2017 at 07:17:03AM +0800, Icenowy Zheng wrote:
> > > >
> > > >
> > > > 23.03.2017, 04:09, "Maxime Ripard" <maxime.ripard@xxxxxxxxxxxxxxxxxx>:
> > > > > On Wed, Mar 22, 2017 at 02:22:22AM +0800, Icenowy Zheng wrote:
> > > > >> Â21.03.2017, 15:41, "Maxime Ripard" <maxime.ripard@xxxxxxxxxxxxxxxxxx>:
> > > > >> Â> On Thu, Mar 16, 2017 at 01:28:04AM +0800, Icenowy Zheng wrote:
> > > > >> Â>> ÂMany Allwinner SoCs after A31 have a CCU in PRCM block.
> > > > >> Â>>
> > > > >> Â>> ÂGive the ones on H3 and A64 compatible strings.
> > > > >> Â>>
> > > > >> Â>> ÂSigned-off-by: Icenowy Zheng <icenowy@xxxxxxxx>
> > > > >> Â>> Â---
> > > > >> Â>> ÂChanges in v2:
> > > > >> Â>> Â- Add iosc for R_CCU's on H3/A64. (A31, A23 and A33 seem to have different
> > > > >> Â>> ÂÂÂclock for mux 3 of ar100 clk. Investgations are needed for them.)
> > > > >> Â>>
> > > > >> Â>> ÂÂDocumentation/devicetree/bindings/clock/sunxi-ccu.txt | 18 +++++++++++++++++-
> > > > >> Â>> ÂÂ1 file changed, 17 insertions(+), 1 deletion(-)
> > > > >> Â>>
> > > > >> Â>> Âdiff --git a/Documentation/devicetree/bindings/clock/sunxi-ccu.txt b/Documentation/devicetree/bindings/clock/sunxi-ccu.txt
> > > > >> Â>> Âindex 68512aa398a9..4a4addff595d 100644
> > > > >> Â>> Â--- a/Documentation/devicetree/bindings/clock/sunxi-ccu.txt
> > > > >> Â>> Â+++ b/Documentation/devicetree/bindings/clock/sunxi-ccu.txt
> > > > >> Â>> Â@@ -7,9 +7,11 @@ Required properties :
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun8i-a23-ccu"
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun8i-a33-ccu"
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun8i-h3-ccu"
> > > > >> Â>> Â+ - "allwinner,sun8i-h3-r-ccu"
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun8i-v3s-ccu"
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun9i-a80-ccu"
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun50i-a64-ccu"
> > > > >> Â>> Â+ - "allwinner,sun50i-a64-r-ccu"
> > > > >> Â>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ- "allwinner,sun50i-h5-ccu"
> > > > >> Â>>
> > > > >> Â>> ÂÂ- reg: Must contain the registers base address and length
> > > > >> Â>> Â@@ -20,7 +22,11 @@ Required properties :
> > > > >> Â>> ÂÂ- #clock-cells : must contain 1
> > > > >> Â>> ÂÂ- #reset-cells : must contain 1
> > > > >> Â>>
> > > > >> Â>> Â-Example:
> > > > >> Â>> Â+For the PRCM CCUs on H3/A64, one more clock is needed:
> > > > >> Â>> Â+- "iosc": another frequency oscillator used for CPUS (usually at 32000Hz,
> > > > >> Â>> Â+ not the same with losc)
> > > > >> Â>
> > > > >> Â> This is called the internal oscillator in the datasheet, it would
> > > > >> Â> probably make more sense to call it that way in the documentation too.
> > > > >> Â>
> > > > >> Â> This oscillator seems to be clocked at 16MHz, so we should represent
> > > > >> Â> it as such.
> > > > >> Â>
> > > > >> Â> And I'm wondering, are you *sure* that it's fed directly from the
> > > > >> Â> internal oscillator, or goes through the registers in the RTC, with
> > > > >> Â> the 32 divider and 16 prescaler by default that makes it at roughly
> > > > >> Â> the same rate (31.25kHz).
> > > > >>
> > > > >> ÂIn fact I know nothing about it -- I only represented the code in BSP
> > > > >> Âclock driver.
> > > > >>
> > > > >> ÂThe mux value 3 varies from SoC to SoC. For A64/H5 it's 32000,
> > > > >> Âfor A33 it's 667000 (seems to be directly the internal OSC, as the
> > > > >> Âuser manual says the internal OSC is 600~700kHz; but it's named
> > > > >> Âcpuosc rather than iosc in A33 BSP clock driver); for A80 it's even
> > > > >> ÂPLL_AUDIO.
> > > > >
> > > > > Where are you getting those info from?
> > > > >
> > > > > As far as I know, the A33 PRCM takes the hosc, losc, pll6 and CPU
> > > > > (internal) oscillator:
> > > > > https://github.com/allwinner-zh/linux-3.4-sunxi/blob/master/drivers/clk/sunxi/clk-sun8iw5.c#L508
> > > > >
> > > > > The H3 takes the hosc and losc:
> > > > > https://github.com/allwinner-zh/linux-3.4-sunxi/blob/master/drivers/clk/sunxi/clk-sun8iw7.c#L379
> > > > >
> > > > > The A80 takes the hosc and losc:
> > > > > https://github.com/allwinner-zh/linux-3.4-sunxi/blob/master/drivers/clk/sunxi/clk-sun9iw1.c#L281
> > > > >
> > > > > The A64 takes the hosc, losc, pll-periph0 and the iosc, which indeed
> > > > > seems to be fed from the internal oscillator with the divider in the
> > > > > RTC:
> > > > > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65-bsp2.0/arch/arm64/boot/dts/sun50iw1p1-clk.dtsi#L19
> > > > > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65-bsp2.0/drivers/clk/sunxi/clk-sun50iw1.c#L603
> > > >
> > > > But then in sunxi_init_clocks function, the iosc clock is initialized
> > > > as a fixed clock with 32000Hz.
> > > >
> > > > The clock node in BSP device tree have a compatible of
> > > > allwinner,fixed-clock, but not fixed-clock, which makes it not able
> > > > to be really probed.
> > >
> > > That clock is registered:
> > > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65-bsp2.0/drivers/clk/sunxi/clk-sun50iw1.c#L1193
> > >
> >
> > Oh yes, but conflicts exist between the iosc registered in
> > clk-sun50iw1.c and described in sun50iw1p1-clk.dtsi . The former is
> > 32000, and the latter is 16000000.
>
> No, it is 16MHz / 32 / 16 = 31.25 kHz
>
> > What should we do then?
> >
> > (Maybe it will be better to temporarily ignore this mux, as it's
> > difficult to finally find out this correct mux...)
>
> That is not an option, we will not be able to fix it afterwards.
>
> What we should do is getting an actual idea of what's going on, and
> not just hacking something together hoping it will work.
>
> You can start by figuring out how the Allwinner clock driver actually
> works and / or by trying the various muxing options with something you
> can measure the frequency with. The i2c or uart coupled with a scope
> or logical analyzer would be a great fit for that.
>
> Using the PRCM timer is another option and you can measure the
> frequency it counts at.

The MUX 3 of AR100 is surely Internal OSC on A64/H3/H5.

Some measurement done with AR100 (all in Hz):

H5 (Orange Pi PC2):
16351952
16347120
16343624

A64 (Pine64+):
11192560
11174128
11174992

H3 (Orange Pi One):
15676016
15625088
15600144

H2+ (Orange Pi Zero):
15907560
15823768
15805144

Seems that on H3/H5 the IOSC is ~16MHz, but on A64 it's... ~12MHz?
(Although the usermanual says 16Mhz in the chapter of RTC)

Maybe some further investigations should be done on more boards.

A fork of ar100-info is at
https://github.com/Icenowy/ar100-info/tree/hz-test ,
which contains IOSC frequency calculation and show in Hz. (and of
course H5/A64 support)

> Maxime