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

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Message-ID: <aWEDr3O9T7bASnj9@aspen.lan>
Date: Fri, 9 Jan 2026 13:33:35 +0000
From: Daniel Thompson <danielt@...nel.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Cc: barnabas.czeman@...nlining.org, 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 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).

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.