[PATCH v8 0/5] auxdisplay: add support for TI LP5812 4x3 Matrix LED driver

[Pavel Machek]

Hi!

> > > Thank you, Pavel, for the confirmation.
> > > Thank you, Geert, for the review and the question.
> > > 
> > > I would like to make it clearer.
> > > 
> > > On Mon, 28 Apr 2025 Geert Uytterhoeven wrote:
> > > 
> > 
> > > > > > > - Move driver to drivers/auxdisplay/ instead of drivers/leds/.
> > > > > > > - Rename files from leds-lp5812.c/.h to lp5812.c/.h.
> > > > > > > - Move ti,lp5812.yaml binding to auxdisplay/ directory,
> > > > > > >   and update the title and $id to match new path.
> > > > > > > - No functional changes to the binding itself (keep Reviewed-by).
> > > > > > > - Update commit messages and patch titles to reflect the move.
> > > > > > > - Link to v7: https://lore.kernel.org/linux-leds/20250422190121.46839-1-trannamatk@gmail.com/
> > > > > >
> > > > > > Out of sudden without discussing with auxdisplay maintainers/reviewers?
> > > > > > Thanks, no.
> > > > > > Please, put into the cover letter the meaningful summary of what's
> > > > > > going on and why this becomes an auxdisplay issue. Brief review of the
> > > > > > bindings sounds more likely like LEDS or PWM subsystems.
> > > > >
> > > > > It is 4x3 matrix. That means it is not suitable for LEDs. I don't
> > > > > believe it is suitable for PWM, either -- yes, it is 36 PWM outputs,
> > > > > but...
> > > > 
> > > > 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.

Show us one device where it is used, photo would be best. I suspect
that the router use might indeed qualify for LED subsystem.

You described is at 4x3 display, but it is really used as 4xRGB?

> Given that, it seems to match the LED subsystem better than auxdisplay, doesn't it?

Seems so, yes. From description, I assumed it was 4x3xRGB, not 4xRGB.

Best regards,
								Pavel
-- 
I don't work for Nazis and criminals, and neither should you.
Boycott Putin, Trump, and Musk!
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 195 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20250508/9209a464/attachment.sig>