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From: Pavel Machek <pavel@ucw.cz>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Dan Murphy <dmurphy@ti.com>, Rob Herring <robh+dt@kernel.org>,
	Andy Gross <agross@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>,
	Lee Jones <lee.jones@linaro.org>,
	Martin Botka <martin.botka1@gmail.com>,
	linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-pwm@vger.kernel.org
Subject: Re: [PATCH v6 2/4] leds: Add driver for Qualcomm LPG
Date: Thu, 29 Apr 2021 23:12:23 +0200	[thread overview]
Message-ID: <20210429211223.GA5480@amd> (raw)
In-Reply-To: <YIn50NW+Pimqfsih@builder.lan>

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Hi!

> > > +static int lpg_add_pwm(struct lpg *lpg)
> > > +{
> > > +	int ret;
> > > +
> > > +	lpg->pwm.base = -1;
> > > +	lpg->pwm.dev = lpg->dev;
> > > +	lpg->pwm.npwm = lpg->num_channels;
> > > +	lpg->pwm.ops = &lpg_pwm_ops;
> > > +
> > > +	ret = pwmchip_add(&lpg->pwm);
> > > +	if (ret)
> > > +		dev_err(lpg->dev, "failed to add PWM chip: ret %d\n", ret);
> > > +
> > > +	return ret;
> > > +}
> > 
> > Do we need to do this? I'd rather have LED driver, than LED+PWM
> > driver...
> > 
> 
> Yes, I believe we need to do this.
> 
> Because each piece of hardware has N channels, which can be wired to
> LEDs, grouped with other channels and wired to multicolor LEDs or be
> used as PWM signals. And this configuration is board specific.
> 
> One such example is the laptop in front of me, which has 3 channels
> wired to an RGB LED and 1 channel wired as a backlight control signal
> (i.e. using pwm-backlight).  Another example is a devboard where the
> 4 channels are wired to 4 LEDs.

Ok, so this is actually important. In this case you should have PWM
layer, exporting PWMs, and then rgb-LED driver that takes three of
those PWMs and turns them into LED, no?

And ... surprise ... that is likely to help other people, as LEDs
connected to PWMs are quite common.

Hmm.?

If you can't do this for some reason, you should probably explain in
the changelog, because this is going to be FAQ.

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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  reply	other threads:[~2021-04-29 21:12 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-21 20:12 [PATCH v6 0/4] Qualcomm Light Pulse Generator Bjorn Andersson
2020-10-21 20:12 ` [PATCH v6 1/4] dt-bindings: leds: Add Qualcomm Light Pulse Generator binding Bjorn Andersson
2020-10-26 15:02   ` Rob Herring
2020-10-21 20:12 ` [PATCH v6 2/4] leds: Add driver for Qualcomm LPG Bjorn Andersson
2020-10-22 19:25   ` Luca Weiss
2020-10-29 18:13   ` Pavel Machek
2021-04-29  0:12     ` Bjorn Andersson
2021-04-29 21:12       ` Pavel Machek [this message]
2021-04-29 21:29         ` Bjorn Andersson
2021-05-04 15:43           ` Pavel Machek
2021-05-04 16:13             ` Bjorn Andersson
2021-05-05  5:21               ` Uwe Kleine-König
2021-04-18 21:54   ` Marijn Suijten
2021-04-28 22:39     ` Bjorn Andersson
2021-04-29 19:31       ` Marijn Suijten
2021-04-29 20:54         ` Bjorn Andersson
2021-05-05  5:15   ` Uwe Kleine-König
2021-05-05  5:19     ` Uwe Kleine-König
2021-05-13 17:43     ` Bjorn Andersson
2020-10-21 20:12 ` [PATCH v6 3/4] arm64: dts: qcom: pm(i)8994: Add mpp and lpg blocks Bjorn Andersson
2020-10-21 20:12 ` [PATCH v6 4/4] arm64: dts: qcom: Add user LEDs on db820c Bjorn Andersson
2021-04-15 10:46 [PATCH v6 2/4] leds: Add driver for Qualcomm LPG Yassine Oudjana

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