[PATCH 07/13] ARM: dts: r8a7792: initial SoC device tree

Hi Sergei,

On Mon, Jun 13, 2016 at 1:24 PM, Sergei Shtylyov
[off-list ref] wrote:

On 6/13/2016 10:12 AM, Geert Uytterhoeven wrote:

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   The only problem I'm seeing (again) is the RCAN clock failing to
register:

rcar_gen2_cpg_clocks_init: failed to register cpg_clocks rcan clock
(-12)

   I was going to look at it yesterday but (wrongly) thought it somehow
cured itself... I'll look at it now.

The RCAN parent is the second clock in the CPG node's "clocks" property,
which you didn't provide.

   Actually, the things are more complex. The figure 7.1c suggests that
the
RCAN clock has different parent on R8A7792 than on the other SoCs --
namely
PLL1/VCO 1/4. That may be, since there's just no USB_EXTAL signal on this
SoC (it doesn't seem to support any USB IPs). Which means the
'clk-rcar-gen2' driver can't work with the RCAN clock in its current
form.

Right, I had forgotten about that.
Fortunately the clk-rcar-gen2 driver has a sane failure mode for this case
;-)

   What do you mean?

I mean that it failed due to the missing parent clock, instead of continuing
silently with a wrong clock rate.

quoted

it seems the RCAN clock can just be modeled as a fixed clock. However,
its divider value isn't clear to me,

   IIRC, the fixed RCAN divisor was equal to 6.

1560 / 6 != 15.9.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds