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Date:   Mon, 8 Nov 2021 16:16:13 +0100
From:   Ansuel Smith <ansuelsmth@gmail.com>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>, Pavel Machek <pavel@ucw.cz>,
        John Crispin <john@phrozen.org>, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-leds@vger.kernel.org,
        Marek =?iso-8859-1?Q?Beh=FAn?= <kabel@kernel.org>
Subject: Re: [RFC PATCH v2 1/5] leds: trigger: add API for HW offloading of
 triggers
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References: <20211108002500.19115-1-ansuelsmth@gmail.com>
 <20211108002500.19115-2-ansuelsmth@gmail.com>
 <YYkuZwQi66slgfTZ@lunn.ch>
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On Mon, Nov 08, 2021 at 03:04:23PM +0100, Andrew Lunn wrote:
> > +static inline int led_trigger_offload(struct led_classdev *led_cdev)
> > +{
> > +	int ret;
> > +
> > +	if (!led_cdev->trigger_offload)
> > +		return -EOPNOTSUPP;
> > +
> > +	ret = led_cdev->trigger_offload(led_cdev, true);
> > +	led_cdev->offloaded = !ret;
> > +
> > +	return ret;
> > +}
> > +
> > +static inline void led_trigger_offload_stop(struct led_classdev *led_cdev)
> > +{
> > +	if (!led_cdev->trigger_offload)
> > +		return;
> > +
> > +	if (led_cdev->offloaded) {
> > +		led_cdev->trigger_offload(led_cdev, false);
> > +		led_cdev->offloaded = false;
> > +	}
> > +}
> > +#endif
> 
> I think there should be two calls into the cdev driver, not this
> true/false parameter. trigger_offload_start() and
> trigger_offload_stop().
> 

To not add too much function to the struct, can we introduce one
function that both enable and disable the hw mode?

> There are also a number of PHYs which don't allow software blinking of
> the LED. So for them, trigger_offload_stop() is going to return
> -EOPNOTSUPP. And you need to handle that correctly.
> 

So we have PHYs that can only work in offload or off. Correct?

> It would be go to also document the expectations of
> trigger_offload_stop(). Should it leave the LED in whatever state it
> was, or force it off? 
>

I think it should be put off. Do you agree? (also the brightness should
be set to 0 in this case)

>      Andrew

-- 
	Ansuel