Re: [PATCH v5 2/2] leds: mt6360: Add LED driver for MT6360

[Jacek Anaszewski]

On 10/30/20 9:51 AM, Gene Chen wrote:
> Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> 於 2020年10月28日 週三 上午1:28寫道：
> > On 10/27/20 10:28 AM, Gene Chen wrote:
> > > Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> 於 2020年10月21日 週三 上午5:47寫道：
> > > > On 10/20/20 8:44 AM, Gene Chen wrote:
> > > > > Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> 於 2020年10月9日 週五 上午5:51寫道：
> > > > > > Hi Gene,
> > > > > >
> > > > > > On 10/7/20 3:42 AM, Gene Chen wrote:
> > > > > > > From: Gene Chen <gene_chen@xxxxxxxxxxx>
> > > > > > >
> > > > > > > Add MT6360 LED driver include 2-channel Flash LED with torch/strobe mode,
> > > > > > > 3-channel RGB LED support Register/Flash/Breath Mode, and 1-channel for
> > > > > > > moonlight LED.
> > > > > > >
> > > > > > > Signed-off-by: Gene Chen <gene_chen@xxxxxxxxxxx>
> > > > > > > ---
> > > > > > >      drivers/leds/Kconfig       |  12 +
> > > > > > >      drivers/leds/Makefile      |   1 +
> > > > > > >      drivers/leds/leds-mt6360.c | 783 +++++++++++++++++++++++++++++++++++++++++++++
> > > > > > >      3 files changed, 796 insertions(+)
> > > > > > >      create mode 100644 drivers/leds/leds-mt6360.c
> > > > > > >
> > > > > > > diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> > > > > > > index 1c181df..c7192dd 100644
> > > > > > > --- a/drivers/leds/Kconfig
> > > > > > > +++ b/drivers/leds/Kconfig
> > > > > > > @@ -271,6 +271,18 @@ config LEDS_MT6323
> > > > > > >            This option enables support for on-chip LED drivers found on
> > > > > > >            Mediatek MT6323 PMIC.
> > > > > > >
> > > > > > > +config LEDS_MT6360
> > > > > > > +     tristate "LED Support for Mediatek MT6360 PMIC"
> > > > > > > +     depends on LEDS_CLASS_FLASH && OF
> > > > > > > +     depends on LEDS_CLASS_MULTICOLOR
> > > > > >
> > > > > > Since CONFIG_LED_CLASS_MULTICOLOR can be turned off you need to have
> > > > > > below instead:
> > > > > >
> > > > > > depends on LEDS_CLASS_MULTICOLOR || !!LEDS_CLASS_MULTICOLOR
> >
> > My typo here, should be one "!":
> >
> > depends on LEDS_CLASS_MULTICOLOR || !LEDS_CLASS_MULTICOLOR
> >
> > And you should also have
> >
> > depends on LEDS_CLASS_FLASH || !LEDS_CLASS_FLASH
> >
> > But to make it work correctly you would have to add registration
> > stubs to include/linux/led-class-flash.h similarly to LED mc stubs
> > in include/linux/led-class-multicolor.h.
> >
> > > > > > Unless you want to prevent enabling the driver without RGB LED,
> > > > > > but that does not seem to be reasonable at first glance.
> > > > >
> > > > > May I change to "select LEDS_CLASS_MULTICOLOR"?
> > > > > I suppose RGB always use multicolor mode.
> > > >
> > > > You will also have moonlight LED that will not need multicolor
> > > > framework. Is it somehow troublesome to keep "depends on"?
> > >
> > > If only use ML LED and FLED,  DTSI will only define ML LED and FLED.
> > > Therefore, the drivers probe will not register rgb multicolor device.
> >
> > Please test your use case again with my fixed "depends on".
> >
> > In case when there is only ML LED and FLED in the DT it should
> > register both devices if LEDS_CLASS_FLASH is turned on.
> > Multicolor framework has nothing to do in this case.
> >
> > But if you additionally had MC LED node, then it should
> > be registered only if LEDS_CLASS_MULTICOLOR is enabled.
> >
> > Similarly, when FLED node is present, but LEDS_CLASS_FLASH
> > is off, and LEDS_CLASS_MULTICOLOR is on, the driver should still
> > compile, but register only LED MC device (if its node is present).
>
> I think this case only register LED device, not LED "MC" device.
> Because our FLASH is not a multicolor device.

No, here I was describing following setup:

- DT FLED node is present, CONFIG_LEDS_CLASS_FLASH is off
- DT MC node is present, CONFIG_LEDS_CLASS_MULTICOLOR is on

ML LED presence in DT is irrelevant in this case.
It should be always registered if there is corresponding DT node
and LEDS_CLASS is on.

> > Possible should be also the case when both LEDS_CLASS_FLASH
> > and LEDS_CLASS_MULTICOLOR are off. Then only LED class device
> > for ML LED will be registered (provided there is ML DT node).
> > But to make it possible you should have also "depends on LEDS_CLASS"
> > in the Kconfig entry.
>
> According to your suggestion,
> depends on LED_CLASS && LEDS_CLASS_FLASH && OF

s/LED_CLASS/LEDS_CLASS/

And you have to remove LEDS_CLASS_FLASH from above line.

> depends on LEDS_CLASS_MULTICOLOR || !!LEDS_CLASS_MULTICOLOR

s/!!LEDS_CLASS_MULTICOLOR/!LEDS_CLASS_MULTICOLOR/

> depends on LEDS_CLASS_FLASH || !LEDS_CLASS_FLASH
> depends on MFD_MT6360

You will need V4L2_FLASH_LED_CLASS dependency as well, to avoid
build break, when it is set to 'm'.

To recap, following block of dependencies is required:

depends on LEDS_CLASS && OF
depends on LEDS_CLASS_MULTICOLOR || !LEDS_CLASS_MULTICOLOR
depends on LEDS_CLASS_FLASH || !LEDS_CLASS_FLASH
depends on V4L2_FLASH_LED_CLASS || !V4L2_FLASH_LED_CLASS
depends on MFD_MT6360

> and source code add constraint
>
> #if IS_ENABLED(CONFIG_LEDS_CLASS_MULTICOLOR)
>      ret = devm_led_classdev_multicolor_register_ext(parent, &led->rgb,
> init_data);
> #endif
>
> #if IS_ENABLED(CONFIG_LEDS_CLASS_FLASH)
>      ret = devm_led_classdev_flash_register_ext(parent, &led->flash, init_data);
> #endif

No, the guards should be in headers. That's why I recommended adding
no ops for LED flash class registration functions in previous email.

Please compare include/linux/led-class-multicolor.h and do similar 
changes in include/linux/led-class-flash.h.

> =============
>
> Or Should I seperate two drivers?
> one for RGB LED, one for ML LED and FLED

This would incur unnecessary code duplication.

--
Best regards,
Jacek Anaszewski