linux-kernel - Re: [PATCH 0/3] clk: meson: fix mpll jitter

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Message-ID: <CAFBinCCSoJYnSt5L07aK4+wmU54soFxRODuHbxaAqcJpmOL+fg@mail.gmail.com>
Date:   Sat, 30 Mar 2019 16:58:37 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Jerome Brunet <jbrunet@...libre.com>
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] clk: meson: fix mpll jitter

On Fri, Mar 29, 2019 at 4:34 PM Jerome Brunet <jbrunet@...libre.com> wrote:
>
> As reported on this [0] mpll series, We are observing a lot of jitter
> on the MPLL outputs of the g12a. No such jitter is seen on gx family.
> On the axg family, only MPLL2 seems affected.
>
> The jitter can be as high as +/- 4%.
>
> This is a problem for audio application. This may cause distortion on
> i2s and completely break SPDIF.
>
> After exchanging with Amlogic, it seems he have activated (by mistake)
> the 'spread spectrum' feature.
>
> This patchset properly set the bit responsible for the spread spectrum
> in the mpll driver and add the required correction in the related clock
> controllers.
>
> Jerome Brunet (3):
>   clk: meson: mpll: properly handle spread spectrum
this depends on a patch from your other series "clk: meson: fixup g12a
mpll": [0]
personally I would base the other series on this one because this one
contains a "Fixes" that (meaning that the patch will get backported
and that's easier if there aren't any conflicts)


Regards
Martin


[0] https://patchwork.kernel.org/patch/10868837/