linux-kernel - Re: [PATCH v2 2/2] clk: meson: g12a: add cpu clocks

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Date:   Tue, 5 Mar 2019 22:10:08 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     jbrunet@...libre.com, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] clk: meson: g12a: add cpu clocks

On Mon, Mar 4, 2019 at 2:12 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>
> Add the Amlogic G12A Family CPU Clock tree in read/only for now.
>
> The CPU clock can either use the SYS_PLL for > 1GHz frequencies or
> use a couple of div+mux from 1GHz/667MHz/24MHz source with 2 non-glitch
> muxes.
>
> Proper DVFS support will come in a second time.
>
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

in my previous review I criticized that the post-dividers are not
mentioned in the description.
it's not part of v2 but after having a closer look again I think it's
not a big issue:
these CPU post-dividers are all marked as read-only and have a comment
that "ROM monitor code" manages them.

disclaimer for my "reviewed-by":
- I don't have access to the datasheet so I can't verify if the clock
tree from this patch is correct
- the latest buildroot code with G12A support
(buildroot_openlinux_kernel_4.9_fbdev_20180706) doesn't have proper
names for all clocks
- this review is based on my experience with Meson8* (where Linux also
manages the CPU clock, unlike on the GX SoCs where it's managed in
firmware)


Regards
Martin