Re: [PATCH] arm64: dts: renesas: hihope-common: Add LEDs support

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Fabrizio,

On Tue, Jun 18, 2019 at 5:56 PM Fabrizio Castro
<fabrizio.castro@bp.renesas.com> wrote:
> > From: linux-renesas-soc-owner@vger.kernel.org <linux-renesas-soc-owner@vger.kernel.org> On Behalf Of Geert Uytterhoeven
> > Sent: 18 June 2019 16:10
> > Subject: Re: [PATCH] arm64: dts: renesas: hihope-common: Add LEDs support
> >
> > On Fri, Jun 14, 2019 at 3:17 PM Fabrizio Castro
> > <fabrizio.castro@bp.renesas.com> wrote:
> > > This patch adds LEDs support to the HiHope RZ/G2[MN] Main Board
> > > common device tree.
> > >
> > > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> >
> > Thanks for your patch!
> >
> > > --- a/arch/arm64/boot/dts/renesas/hihope-common.dtsi
> > > +++ b/arch/arm64/boot/dts/renesas/hihope-common.dtsi
> > > @@ -17,6 +17,30 @@
> > >                 stdout-path = "serial0:115200n8";
> > >         };
> > >
> > > +       leds {
> > > +               compatible = "gpio-leds";
> > > +
> > > +               led0 {
> > > +                       gpios = <&gpio6 11 GPIO_ACTIVE_HIGH>;
> > > +                       label = "LED0";
> >
> > There's no need for a label property, if it matches the node name
> > (applies to all four LEDs).
>
> I could have used the actual names on the schematic, but then I realised that
> would not have been too helpful due to the corresponding switch names:
> LED0 - GP6_11 - SW2202 - LED2201
> LED1 - GP6_12 - SW2201 - LED2202
> LED2 - GP6_13 - SW2203 - LED2203
> LED3 - GP0_00 - N/A - LED2402
> The first 3 LEDs are found next to the micro USB connector for the debug console,
> the forth LED is found next to the WiFi and BT LEDs.
>
> I thought that using "LEDn" as labels would put a remark on the
> "desired ordering" of the LEDs (even though there is no actual
> requirement for that), but as you pointed out it's probably a bit
> confusing? Do you think I should take the label out?

If the LEDs don't have nice labels on the PCB, I would drop the label
properties.

> > Note that this GPIO is shared with a switch, like on Salvator-X(S) and
> > ULCB.  As currently Linux cannot handle both, describing the LED
> > precludes adding the switch later.
> > (applies to the first 3 LEDs).
>
> Thank you for pointing this out. That's desired behaviour in this case.

OK.

> > > +               led3 {
> > > +                       gpios = <&gpio0  0 GPIO_ACTIVE_HIGH>;
> > > +                       label = "LED3";
> > > +               };
> >
> > I cannot find LED3. According to the schematics GP0_0 == CS0n is used
> > as the chipselect for the LVDS switch?
>
> My understanding is that CS0n is on GP1_20, could you please double
> check?
> (pin name: AJ4) GP0_00 == D0 == ExD0 on the schematic I have, I thought
> you may have been looking at an older version of the schematic, but after
> going through the history it seems like that line has always been there.

Sorry, my mistake.  As there is no GP0_0 in the schematic, I looked up
the pin number in the docs, but ended up using the R-Car M3-W SiP pin
number, instead of the RZ/G2M FCBGA SoC pin number :-(

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds