linux-kernel - [PATCH v2 0/2] rtc: sun6i: Make external oscillator optional

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Message-Id: <20200308135849.106333-1-jernej.skrabec@siol.net>
Date:   Sun,  8 Mar 2020 14:58:47 +0100
From:   Jernej Skrabec <jernej.skrabec@...l.net>
To:     mripard@...nel.org, wens@...e.org
Cc:     robh+dt@...nel.org, a.zummo@...ertech.it,
        alexandre.belloni@...tlin.com,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-rtc@...r.kernel.org
Subject: [PATCH v2 0/2] rtc: sun6i: Make external oscillator optional

This is implementation of idea discussed here:
https://lore.kernel.org/linux-arm-kernel/20200117183901.lkieha3hu6nz2hoj@gilmour.lan/T/

Part of first patch commit message:

Some boards, like OrangePi PC2 (H5), OrangePi Plus 2E (H3) and Tanix TX6
(H6) don't have external 32kHz oscillator. Till H6, it didn't really
matter if external oscillator was enabled because HW detected error and
fall back to internal one. H6 has same functionality but it's the first
SoC which have "auto switch bypass" bit documented and always enabled in
driver. This prevents RTC to work correctly if external crystal is not
present on board. There are other side effects - all peripherals which
depends on this clock also don't work (HDMI CEC for example).

In this series I fixed only H6 based boards since improper settings have
real impact due to explicitly forbidden fallback to internal oscillator.
Since most boards actually contain external oscillator, I wonder if it's
better to leave external oscillator in common H6 dtsi and just delete
clocks property in rtc node and ext. oscillator node in board dts file?

What do you think?

Best regards,
Jernej

Changes from v1:
- added comments to driver to make more clear how clock registration
  works

Jernej Skrabec (2):
  rtc: sun6i: Make external 32k oscillator optional
  arm64: dts: allwinner: h6: Move ext. oscillator to board DTs

 .../boot/dts/allwinner/sun50i-h6-beelink-gs1.dts | 11 +++++++++++
 .../boot/dts/allwinner/sun50i-h6-orangepi-3.dts  | 11 +++++++++++
 .../boot/dts/allwinner/sun50i-h6-orangepi.dtsi   | 11 +++++++++++
 .../boot/dts/allwinner/sun50i-h6-pine-h64.dts    | 11 +++++++++++
 arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi     |  8 --------
 drivers/rtc/rtc-sun6i.c                          | 16 ++++++++--------
 6 files changed, 52 insertions(+), 16 deletions(-)

-- 
2.25.1