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Date: Thu, 17 May 2018 07:31:35 -0500
From: Rob Herring <robh+dt@...nel.org>
To: Kiran Gunda <kgunda@...eaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>,
Lee Jones <lee.jones@...aro.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
Jingoo Han <jingoohan1@...il.com>,
Jacek Anaszewski <jacek.anaszewski@...il.com>,
Pavel Machek <pavel@....cz>,
Mark Rutland <mark.rutland@....com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Linux LED Subsystem <linux-leds@...r.kernel.org>,
devicetree@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
dri-devel <dri-devel@...ts.freedesktop.org>,
linux-fbdev@...r.kernel.org,
linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH V1 2/5] backlight: qcom-wled: Add support for WLED4 peripheral
On Thu, May 17, 2018 at 4:47 AM, <kgunda@...eaurora.org> wrote:
> On 2018-05-08 15:55, kgunda@...eaurora.org wrote:
>>
>> On 2018-05-07 21:50, Bjorn Andersson wrote:
>>>
>>> On Thu 03 May 02:57 PDT 2018, Kiran Gunda wrote:
>>>
>>>> WLED4 peripheral is present on some PMICs like pmi8998
>>>> and pm660l. It has a different register map and also
>>>> configurations are different. Add support for it.
>>>>
>>>
>>> Several things are going on in this patch, it needs to be split to
>>> not hide the functional changes from the structural/renames.
>>>
>> Ok. I will split it in the next series.
>>>>
>>>> Signed-off-by: Kiran Gunda <kgunda@...eaurora.org>
>>>> ---
>>>> .../bindings/leds/backlight/qcom-wled.txt | 172 ++++-
>>>> drivers/video/backlight/qcom-wled.c | 749
>>>> +++++++++++++++------
>>>> 2 files changed, 696 insertions(+), 225 deletions(-)
>>>>
>>>> diff --git
>>>> a/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
>>>> b/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
>>>> index fb39e32..0ceffa1 100644
>>>> --- a/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
>>>> +++ b/Documentation/devicetree/bindings/leds/backlight/qcom-wled.txt
>>>> @@ -1,30 +1,129 @@
>>>> Binding for Qualcomm Technologies, Inc. WLED driver
>>>>
>>>> -Required properties:
>>>> -- compatible: should be "qcom,pm8941-wled"
>>>> -- reg: slave address
>>>> -
>>>> -Optional properties:
>>>> -- default-brightness: brightness value on boot, value from: 0-4095
>>>> - default: 2048
>>>> -- label: The name of the backlight device
>>>> -- qcom,cs-out: bool; enable current sink output
>>>> -- qcom,cabc: bool; enable content adaptive backlight control
>>>> -- qcom,ext-gen: bool; use externally generated modulator signal to dim
>>>> -- qcom,current-limit: mA; per-string current limit; value from 0 to 25
>>>> - default: 20mA
>>>> -- qcom,current-boost-limit: mA; boost current limit; one of:
>>>> - 105, 385, 525, 805, 980, 1260, 1400, 1680
>>>> - default: 805mA
>>>> -- qcom,switching-freq: kHz; switching frequency; one of:
>>>> - 600, 640, 685, 738, 800, 872, 960, 1066, 1200, 1371,
>>>> - 1600, 1920, 2400, 3200, 4800, 9600,
>>>> - default: 1600kHz
>>>> -- qcom,ovp: V; Over-voltage protection limit; one of:
>>>> - 27, 29, 32, 35
>>>> - default: 29V
>>>> -- qcom,num-strings: #; number of led strings attached; value from 1 to
>>>> 3
>>>> - default: 2
>>>> +WLED (White Light Emitting Diode) driver is used for controlling
>>>> display
>>>> +backlight that is part of PMIC on Qualcomm Technologies, Inc. reference
>>>> +platforms. The PMIC is connected to the host processor via SPMI bus.
>>>> +
>>>> +- compatible
>>>> + Usage: required
>>>> + Value type: <string>
>>>> + Definition: should be "qcom,pm8941-wled" or
>>>> "qcom,pmi8998-wled".
>>>> + or "qcom,pm660l-wled".
>>>
>>>
>>> Better written as
>>>
>>> should be one of:
>>> X
>>> Y
>>> Z
>>>
>> Will do it in the next series.
>>>>
>>>> +
>>>> +- reg
>>>> + Usage: required
>>>> + Value type: <prop encoded array>
>>>> + Definition: Base address of the WLED modules.
>>>> +
>>>> +- interrupts
>>>> + Usage: optional
>>>> + Value type: <prop encoded array>
>>>> + Definition: Interrupts associated with WLED. Interrupts can be
>>>> + specified as per the encoding listed under
>>>> + Documentation/devicetree/bindings/spmi/
>>>> + qcom,spmi-pmic-arb.txt.
>>>
>>>
>>> Better to describe that this should be the "short" and "ovp" interrupts
>>> in this property than in the interrupt-names.
>>>
>> Ok. I will do it in the next series.
>>>>
>>>> +
>>>> +- interrupt-names
>>>> + Usage: optional
>>>> + Value type: <string>
>>>> + Definition: Interrupt names associated with the interrupts.
>>>> + Must be "short" and "ovp". The short circuit
>>>> detection
>>>> + is not supported for PM8941.
>>>> +
>>>> +- label
>>>> + Usage: required
>>>> + Value type: <string>
>>>> + Definition: The name of the backlight device
>>>> +
>>>> +- default-brightness
>>>> + Usage: optional
>>>> + Value type: <u32>
>>>> + Definition: brightness value on boot, value from: 0-4095
>>>> + Default: 2048
>>>> +
>>>> +- qcom,current-limit
>>>> + Usage: optional
>>>> + Value type: <u32>
>>>> + Definition: uA; per-string current limit
>>>
>>>
>>> You can't change unit on an existing property, that breaks any existing
>>> dts using the qcom,pm8941-wled compatible.
>>>
>>
>>>> + value:
>>>> + For pm8941: from 0 to 25000 with 5000 ua step
>>>> + Default 20000 uA
>>>> + For pmi8998: from 0 to 30000 with 5000 ua step
>>>> + Default 25000 uA.
>>>
>>>
>>> These values could be described just as well in mA, so keep the original
>>> unit - in particular since the boot-limit is in mA...
>>>
>> Ok. Will keep the original as is in the next series.
>
> Here, I may have to go with the approach as in "qcom,ovp". Because for
> pm8941
> the current step is 1 mA (I have wrongly mentioned as 5000uA here) and for
> PMI8998
> the current step is 2.5 mA. Hence, I will add another variable
> "qcom,current-limit-ua"
> just like "qcom,ovp-mv".
Use unit suffixes defined in bindings/property-units.txt.
Rob
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