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

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Message-Id: <20190329153325.23869-1-jbrunet@baylibre.com>
Date:   Fri, 29 Mar 2019 16:33:22 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     Jerome Brunet <jbrunet@...libre.com>,
        linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 0/3] clk: meson: fix mpll jitter

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
  clk: meson: gxbb: no spread spectrum on mpll0
  clk: meson: axg: spread spectrum is on mpll2

 drivers/clk/meson/axg.c      | 10 +++++-----
 drivers/clk/meson/clk-mpll.c |  9 ++++++---
 drivers/clk/meson/clk-mpll.h |  1 +
 drivers/clk/meson/gxbb.c     |  5 -----
 4 files changed, 12 insertions(+), 13 deletions(-)

-- 
2.20.1