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

[Nam Tran]

On Mon, 28 Apr 2025 Pavel Machek wrote:

> 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.

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

Best regards,
Nam Tran