linux-kernel - RE: [PATCH V4 1/2] dt-bindings: leds: pwm: add enable-gpios property

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID:
 <AM9PR06MB795541A95E9A1089CA95AC1ED742A@AM9PR06MB7955.eurprd06.prod.outlook.com>
Date: Fri, 4 Jul 2025 08:35:38 +0000
From: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: "lee@...nel.org" <lee@...nel.org>, "pavel@...nel.org" <pavel@...nel.org>,
	"robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	GEO-CHHER-bsp-development <bsp-development.geo@...ca-geosystems.com>
Subject: RE: [PATCH V4 1/2] dt-bindings: leds: pwm: add enable-gpios property



> -----Original Message-----
> From: Krzysztof Kozlowski <krzk@...nel.org>
> Sent: Friday, July 4, 2025 3:51 PM
> To: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
> Cc: lee@...nel.org; pavel@...nel.org; robh@...nel.org; krzk+dt@...nel.org;
> conor+dt@...nel.org; linux-leds@...r.kernel.org; devicetree@...r.kernel.org;
> linux-kernel@...r.kernel.org; GEO-CHHER-bsp-development
> <bsp-development.geo@...ca-geosystems.com>
> Subject: Re: [PATCH V4 1/2] dt-bindings: leds: pwm: add enable-gpios property
> 
> This email is not from Hexagon’s Office 365 instance. Please be careful while
> clicking links, opening attachments, or replying to this email.
> 
> 
> On Thu, Jul 03, 2025 at 11:36:10AM +0000, LI Qingwu wrote:
> >
> >
> > > -----Original Message-----
> > > From: Krzysztof Kozlowski <krzk@...nel.org>
> > > Sent: Thursday, July 3, 2025 6:55 PM
> > > To: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>; lee@...nel.org;
> > > pavel@...nel.org; robh@...nel.org; krzk+dt@...nel.org;
> > > conor+dt@...nel.org; linux-leds@...r.kernel.org;
> > > conor+devicetree@...r.kernel.org;
> > > linux-kernel@...r.kernel.org
> > > Cc: GEO-CHHER-bsp-development
> > > <bsp-development.geo@...ca-geosystems.com>
> > > Subject: Re: [PATCH V4 1/2] dt-bindings: leds: pwm: add enable-gpios
> > > property
> > >
> > > This email is not from Hexagon’s Office 365 instance. Please be
> > > careful while clicking links, opening attachments, or replying to this email.
> > >
> > >
> > > On 03/07/2025 12:27, LI Qingwu wrote:
> > > >
> > > >
> > > >> -----Original Message-----
> > > >> From: Krzysztof Kozlowski <krzk@...nel.org>
> > > >> Sent: Thursday, July 3, 2025 5:59 PM
> > > >> To: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>;
> > > >> lee@...nel.org; pavel@...nel.org; robh@...nel.org;
> > > >> krzk+dt@...nel.org;
> > > >> conor+dt@...nel.org; linux-leds@...r.kernel.org;
> > > >> conor+devicetree@...r.kernel.org;
> > > >> linux-kernel@...r.kernel.org
> > > >> Cc: GEO-CHHER-bsp-development
> > > >> <bsp-development.geo@...ca-geosystems.com>
> > > >> Subject: Re: [PATCH V4 1/2] dt-bindings: leds: pwm: add
> > > >> enable-gpios property
> > > >>
> > > >> This email is not from Hexagon’s Office 365 instance. Please be
> > > >> careful while clicking links, opening attachments, or replying to this email.
> > >
> > > Please drop this, it is not relevant in upstream discussions. Use
> > > normal email client which will not produce useless header above.
> > >
> > >
> > > >>
> > > >>
> > > >> On 03/07/2025 11:34, LI Qingwu wrote:
> > > >>> some pwm led driver chips like tps92380 require a separate
> > > >>> enable signal
> > > >>
> > > >> Sentence starts with capital letter.
> > > >>
> > > >> tps92380 does not have dedicated enable pin. It has VDDIO, which
> > > >> serves also enable purpose, but it is a supply.
> > > >
> > > > So this patch is unacceptable anyway?
> > >
> > > If you make this patch for tps92380, I think it is not correct. You
> > > have entire commit msg to explain the hardware and all unusual
> > > things. Having VDDIO and EN pin is unusual, because you do not supply
> power directly from GPIOs of a SoC.
> > > All this should be explained.
> >
> > Thank you for the feedback, what about rename to power-supply with
> regulator support ?
> > Convert this patch to add regulator support instead of GPIO, using
> > "power-supply" property to control LED power, or drop this patch and give up
> upstream, or what's the better from your point of view?
> > appreciate your guidance!
> 
> Does it solve your problem? It is surprising that once you say it is GPIO and once
> as regulator. How is it in your board?
> 
> Regulator is looking as correct hardware description, so that patch would be
> fine.


Thank you for your feedback and clarification.
On our hardware, the TPS92380's VDDIO/EN pin is connected to a GPIO,
which is used to enable or disable the device.
According to the datasheet, this pin is described as 
"enable input for the device as well as supply input (VDDIO) for digital 
pins". If describing this as a supply is the preferred and correct way for
upstream, I can implement as supply regulator controlled by GPIO, and to
model this behavior in device tree. 

or if you have a better suggestion for such cases.

> 
> Best regards,
> Krzysztof