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Date:   Fri, 06 Nov 2020 16:58:04 +0000
To:     Pavel Machek <pavel@ucw.cz>, Dan Murphy <dmurphy@ti.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Rob Herring <robh+dt@kernel.org>
From:   =?utf-8?Q?N=C3=ADcolas_F=2E_R=2E_A=2E_Prado?= 
        <nfraprado@protonmail.com>
Cc:     linux-leds@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        Brian Masney <masneyb@onstation.org>,
        Luca Weiss <luca@z3ntu.xyz>,
        Russell King <linux@armlinux.org.uk>,
        Georgi Djakov <georgi.djakov@linaro.org>,
        linux-kernel@vger.kernel.org, lkcamp@lists.libreplanetbr.org,
        andrealmeid@collabora.com
Reply-To: =?utf-8?Q?N=C3=ADcolas_F=2E_R=2E_A=2E_Prado?= 
          <nfraprado@protonmail.com>
Subject: [RFC PATCH 0/3] Add support for the flash LED on Nexus 5
Message-ID: <20201106165737.1029106-1-nfraprado@protonmail.com>
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Hi,

this patch series adds support for the flash LED on Nexus 5.

The first patch adds the driver for the QPNP flash LED. The code for the dr=
iver
was ported from [1], which was for the 3.4 kernel. That driver originally
supported multiple LED types: WLED, Flash/Torch, RGB, MPP and KPDBL as desc=
ribed
in [2], but this port only contains support for Flash/Torch, and the code f=
or
the others was removed just because it was easier to test. Also, it was
originally an SPMI driver, but here I made it into a platform driver that
matches an SPMI device and uses regmap to read and write on the addresses.

The second patch adds the driver as a module in qcom's defconfig, which is =
the
one used by the Nexus 5.

The third patch adds the relevant nodes to Nexus 5's device tree. These nod=
es
were copied from [3] and [4], only changing the flash-boost-supply and
torch-boost-supply properties to point to the regulator nodes already defin=
ed
upstream at qcom-pm8941.dtsi. Again, I'm not sure if the nodes should be ke=
pt on
separate .dtsi as they were downstream, I just did what was easier for test=
ing.

The flash LED can be tested on a Nexus 5 with the following:

To turn the LED on:
echo 1 > /sys/class/leds/led\:flash_torch/brightness

To turn the LED on only for a couple seconds:
echo 1 > /sys/class/leds/led\:flash_0/brightness

From what I understand flash and torch correspond to the same LED, but flas=
h
only stays on for a couple seconds and uses a different voltage regulator.
I'm not sure why there are both flash_0 and flash_1. Both seem to do the sa=
me.

My questions are: Is there something fundamentally wrong with this patch se=
ries?
Is it okay to have the driver only support the flash LEDs from QPNP (at lea=
st
for the time being)?
But also please give me any other feedback.

Thanks,
N=C3=ADcolas

[1] https://github.com/AICP/kernel_lge_hammerhead/blob/n7.1/drivers/leds/le=
ds-qpnp.c
[2] https://github.com/AICP/kernel_lge_hammerhead/blob/n7.1/Documentation/d=
evicetree/bindings/leds/leds-qpnp.txt
[3] https://github.com/AICP/kernel_lge_hammerhead/blob/n7.1/arch/arm/boot/d=
ts/msm-pm8941.dtsi
[4] https://github.com/AICP/kernel_lge_hammerhead/blob/n7.1/arch/arm/boot/d=
ts/msm8974-leds.dtsi
My tree: https://gitlab.com/nfraprado/linux/

N=C3=ADcolas F. R. A. Prado (3):
  leds: Add driver for QPNP flash led
  ARM: qcom_defconfig: Add QPNP flash LED support
  ARM: dts: qcom: msm8974-hammerhead: Add support for the flash LED

 .../qcom-msm8974-lge-nexus5-hammerhead.dts    |   56 +
 arch/arm/configs/qcom_defconfig               |    1 +
 drivers/leds/Kconfig                          |    9 +
 drivers/leds/Makefile                         |    1 +
 drivers/leds/leds-qpnp.c                      | 1351 +++++++++++++++++
 5 files changed, 1418 insertions(+)
 create mode 100644 drivers/leds/leds-qpnp.c

--=20
2.29.2