linux-kernel - Re: [PATCH v2 2/7] backlight: qcom-wled: Support ovp values for PMI8994

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Message-ID: <00d0c357d31463272d786bcc9abfe295@mainlining.org>
Date: Fri, 09 Jan 2026 16:42:57 +0100
From: barnabas.czeman@...nlining.org
To: Daniel Thompson <danielt@...nel.org>
Cc: Konrad Dybcio <konrad.dybcio@....qualcomm.com>, Lee Jones
 <lee@...nel.org>, Jingoo Han <jingoohan1@...il.com>, Pavel Machek
 <pavel@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Bjorn Andersson
 <andersson@...nel.org>, Kiran Gunda <quic_kgunda@...cinc.com>, Helge Deller
 <deller@....de>, Luca Weiss <luca@...aweiss.eu>, Konrad Dybcio
 <konradybcio@...nel.org>, Eugene Lepshy <fekz115@...il.com>, Gianluca Boiano
 <morf3089@...il.com>, Alejandro Tafalla <atafalla@...on.com>,
 dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH v2 2/7] backlight: qcom-wled: Support ovp values for
 PMI8994

On 2026-01-09 14:33, Daniel Thompson wrote:
> On Fri, Jan 09, 2026 at 12:09:11PM +0100, Konrad Dybcio wrote:
>> On 1/9/26 7:36 AM, barnabas.czeman@...nlining.org wrote:
>> > On 2026-01-08 12:28, Daniel Thompson wrote:
>> >> On Thu, Jan 08, 2026 at 04:43:20AM +0100, Barnabás Czémán wrote:
>> >>> WLED4 found in PMI8994 supports different ovp values.
>> >>>
>> >>> Fixes: 6fc632d3e3e0 ("video: backlight: qcom-wled: Add PMI8994 compatible")
>> >>> Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
>> >>> Signed-off-by: Barnabás Czémán <barnabas.czeman@...nlining.org>
>> >>> ---
>> >>>  drivers/video/backlight/qcom-wled.c | 41 +++++++++++++++++++++++++++++++++++--
>> >>>  1 file changed, 39 insertions(+), 2 deletions(-)
>> >>>
>> >>> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
>> >>> index a63bb42c8f8b..5decbd39b789 100644
>> >>> --- a/drivers/video/backlight/qcom-wled.c
>> >>> +++ b/drivers/video/backlight/qcom-wled.c
>> >>> @@ -1244,6 +1244,15 @@ static const struct wled_var_cfg wled4_ovp_cfg = {
>> >>>      .size = ARRAY_SIZE(wled4_ovp_values),
>> >>>  };
>> >>>
>> >>> +static const u32 pmi8994_wled_ovp_values[] = {
>> >>> +    31000, 29500, 19400, 17800,
>> >>> +};
>> >>> +
>> >>> +static const struct wled_var_cfg pmi8994_wled_ovp_cfg = {
>> >>> +    .values = pmi8994_wled_ovp_values,
>> >>> +    .size = ARRAY_SIZE(pmi8994_wled_ovp_values),
>> >>> +};
>> >>> +
>> >>
>> >> Do these *have* to be named after one of the two PMICs that implement
>> >> this OVP range.
>> >>
>> >> Would something like wled4_alternative_ovp_values[] (and the same
>> >> throughout the patch) be more descriptive?
>> > I don't know. I don't like the PMIC naming either but at least it
>> > descriptive about wich PMIC is needing these values.
> 
> It's the descriptive but wrong element I dislike (pmi8994_wled_ovp_cfg
> is used by pmi8550).
No, pmi8950 is using pmi8994_wled_opts struct what is using 
pmi8994_wled_ovp_cfg.
> 
> I know these things crop up for "historical reasons" when is appears in
> the same patchset I have to question the naming.
> 
> 
>> > I think PMIC naming would be fine if compatibles what representing the
>> > same configurations would be deprecated and used as a fallback compatbile
>> > style.
>> > I mean we could kept the first added compatible for a configuration.
>> > Maybe they should be named diferently i don't know if WLEDs have subversion.
>> 
>> Every PMIC peripheral is versioned.
>> 
>> WLED has separate versioning for the digital and analog parts:
>> 
>> PMIC		ANA	DIG
>> ---------------------------
>> PMI8937		2.0	1.0 (also needs the quirk)
>> PMI8950		2.0	1.0
>> PMI8994		2.0	1.0
>> PMI8996		2.1	1.0
>> PMI8998		3.1	3.0
>> PM660L		4.1	4.0
>> 
>> I don't know for sure if "PMIC4 with WLED ANA/DIG 3.x" a good
>> discriminant though..
> 
> Peronally I'd prefer that to making them all use pmi8994 structures.
> It's a much better link back to the docs (at least for those with the
> power to read them ;-) ).
> 
> 
> Daniel.