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From: Pavel Machek <pavel@ucw.cz>
To: Nam Tran <trannamatk@gmail.com>
Cc: andy@kernel.org, geert@linux-m68k.org, robh@kernel.org,
	krzk+dt@kernel.org, conor+dt@kernel.org,
	christophe.jaillet@wanadoo.fr, corbet@lwn.net,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, florian.fainelli@broadcom.com,
	bcm-kernel-feedback-list@broadcom.com,
	linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v8 0/5] auxdisplay: add support for TI LP5812 4x3 Matrix LED driver
Date: Wed, 30 Apr 2025 09:15:07 +0200	[thread overview]
Message-ID: <aBHN+395kaIdbBEm@duo.ucw.cz> (raw)
In-Reply-To: <20250429170220.8145-1-trannamatk@gmail.com>

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Hi!

> > > > Is it intended to be used as a 4x3 matrix, or is this just an internal
> > > > wiring detail, and should it be exposed as 12 individual LEDs instead?
> > > 
> > > The 4×3 matrix is a real and fundamental aspect of the LP5812’s operation.
> > > It is not just an internal wiring detail.
> > > The device adopts a Time-Cross-Multiplexing (TCM) structure, where 4 output
> > > pins control 12 LED dots individually through scanning. Each pin includes
> > > both high-side and low-side drive circuits, meaning matrix multiplexing is
> > > required for proper operation — it cannot be treated as 12 completely
> > > independent LEDs.
> > 
> > Scanning is really a detail.
> > 
> > If this is used as rectangular 4x3 display, then it goes to auxdisplay.
> > 
> > If this is used as a power LED, SD activity LED, capslock and numlock
> > ... placed randomly all around the device, then it goes LED subsystem.
> 
> The LP5812 is used for LED status indication in devices like smart speakers,
> wearables, and routers, not as a structured rectangular display.

Well, IIRC it also supports automated animations, and that does not
make sense on LED indicators. So... what device do _you_ have and how
exactly is it used there?

Best regards,
								Pavel
-- 
I don't work for Nazis and criminals, and neither should you.
Boycott Putin, Trump, and Musk!

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  parent reply	other threads:[~2025-04-30  7:33 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-27  8:24 [PATCH v8 0/5] auxdisplay: add support for TI LP5812 4x3 Matrix LED driver Nam Tran
2025-04-27  8:24 ` [PATCH v8 1/5] dt-bindings: auxdisplay: add TI LP5812 4×3 Matrix RGB LED Driver Nam Tran
2025-04-27  8:24 ` [PATCH v8 2/5] " Nam Tran
2025-04-27 16:04   ` Randy Dunlap
2025-04-28 17:39     ` Nam Tran
2025-04-27  8:24 ` [PATCH v8 3/5] docs: ABI: Document LP5812 sysfs interfaces Nam Tran
2025-04-27  8:24 ` [PATCH v8 4/5] docs: auxdisplay: document TI LP5812 RGB LED driver Nam Tran
2025-04-27  8:24 ` [PATCH v8 5/5] arm64: dts: Add LP5812 node for Raspberry Pi 4 Model B Nam Tran
2025-04-27  9:35 ` [PATCH v8 0/5] auxdisplay: add support for TI LP5812 4x3 Matrix LED driver Andy Shevchenko
2025-04-28 10:37   ` Pavel Machek
2025-04-28 11:34     ` Geert Uytterhoeven
2025-04-28 17:29       ` Nam Tran
2025-04-28 20:18         ` Pavel Machek
2025-04-29 17:02           ` Nam Tran
2025-04-29 19:47             ` Andy Shevchenko
2025-05-07 16:42               ` Nam Tran
2025-05-08  8:24                 ` Andy Shevchenko
2025-05-08 13:26                   ` Lee Jones
2025-05-08 14:26                     ` Nam Tran
2025-05-08 14:46                       ` Andy Shevchenko
2025-05-08 15:01                         ` Lee Jones
2025-05-10  7:48                           ` Nam Tran
2025-05-12  6:05                             ` Andy Shevchenko
2025-05-12 17:38                               ` Nam Tran
2025-05-12 17:44                                 ` Andy Shevchenko
2025-05-13  8:35                                   ` Lee Jones
2025-05-13  8:10                                 ` Geert Uytterhoeven
2025-05-13  8:50                                   ` Lee Jones
2025-04-30  7:15             ` Pavel Machek [this message]
2025-05-05  7:24               ` Nam Tran
2025-05-08  8:38             ` Pavel Machek
2025-04-28 16:37   ` Nam Tran

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