linux-kernel - Re: [PATCH v4 06/27] dt-bindings: mfd: add samsung,s2dos05

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Message-ID: <CABTCjFCTKoZK58rXBnTd22J2w_mkPp5=nx292eOwW5dAMbp9OA@mail.gmail.com>
Date: Thu, 19 Sep 2024 15:50:25 +0300
From: Dzmitry Sankouski <dsankouski@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Sebastian Reichel <sre@...nel.org>, Bjorn Andersson <andersson@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Sam Ravnborg <sam@...nborg.org>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Lee Jones <lee@...nel.org>, 
	Dmitry Torokhov <dmitry.torokhov@...il.com>, Pavel Machek <pavel@....cz>, 
	Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
	Uwe Kleine-König <ukleinek@...nel.org>, 
	Chanwoo Choi <cw00.choi@...sung.com>, Simona Vetter <simona@...ll.ch>, 
	cros-qcom-dts-watchers@...omium.org, Konrad Dybcio <konradybcio@...nel.org>, 
	Simona Vetter <simona.vetter@...ll.ch>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	linux-clk@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	devicetree@...r.kernel.org, linux-input@...r.kernel.org, 
	linux-leds@...r.kernel.org, linux-pwm@...r.kernel.org, 
	linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v4 06/27] dt-bindings: mfd: add samsung,s2dos05

пн, 16 сент. 2024 г. в 12:14, Krzysztof Kozlowski <krzk@...nel.org>:
>
> On Fri, Sep 13, 2024 at 06:07:49PM +0300, Dzmitry Sankouski wrote:
> > Add samsung,s2dos05 MFD module binding.
> >
> > Signed-off-by: Dzmitry Sankouski <dsankouski@...il.com>
> >
> > ---
> > Changes in v4:
> > - split long(>80) lines
> > - fix indentation
> > - merge with regulators binding
> > - drop pmic suffix
> > - drop unused labels in example
> > - correct description
> > ---
> >  .../devicetree/bindings/mfd/samsung,s2dos05.yaml   | 99 ++++++++++++++++++++++
> >  MAINTAINERS                                        |  1 +
> >  2 files changed, 100 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/mfd/samsung,s2dos05.yaml b/Documentation/devicetree/bindings/mfd/samsung,s2dos05.yaml
> > new file mode 100644
> > index 000000000000..534434002045
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mfd/samsung,s2dos05.yaml
> > @@ -0,0 +1,99 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/mfd/samsung,s2dos05.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Samsung S2DOS05 Power Management IC
> > +
> > +maintainers:
> > +  - Dzmitry Sankouski <dsankouski@...il.com>
> > +
> > +description:
> > +  This is a device tree bindings for S2DOS family of Power Management IC (PMIC).
>
> Drop this sentence, not really useful. I know that I put it into other
> Samsung PMIC bindings, but let's don't grow this pattern.
>
> > +
> > +  The S2DOS05 is a companion power management IC for the panel and touchscreen
> > +  in smart phones. Provides voltage regulators and
> > +  ADC for power/current measurements.
> > +
> > +  Regulator section has 4 LDO and 1 BUCK regulators and also
> > +  provides ELVDD, ELVSS, AVDD lines.
>
> What are these? Input supplies?
>

ELVSS and ELVDD are common abbreviations for AMOLED panel backlight supplies,
AVDD for panel electronics. I conclude that s2dos05 ic provides
ELVSS, ELVDD, AVDD from the facts, it can measure its current and power.
Those power lines are controlled by display hardware [1],
i.e. vendor kernel driver has no clue how to control those regulators.

I guess they just combined regular regulator ic with ELVSS, ELVDD, AVDD ic
like [2].

[1]: https://github.com/klabit87/twrp_android_samsung_kernel_sdm845/blob/android-8.0/drivers/gpu/drm/msm/samsung/S6E3HA8_AMB577PX01/dsi_panel_S6E3HA8_AMB577PX01_wqhd_octa_cmd.dtsi#L3508
[2]: https://www.st.com/resource/en/data_brief/stmp30.pdf