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Date:   Fri, 21 Sep 2018 08:31:09 +0200
From:   Daniel Golle <daniel@makrotopia.org>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Aditya Prayoga <aditya@kobol.io>, linux-ide@vger.kernel.org,
        linux-leds@vger.kernel.org, Jason Cooper <jason@lakedaemon.net>,
        Andrew Lunn <andrew@lunn.ch>,
        Gregory Clement <gregory.clement@bootlin.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        Jens Axboe <axboe@kernel.dk>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Jacek Anaszewski <jacek.anaszewski@gmail.com>
Subject: Re: [PATCH 1/2] libata: add ledtrig support
Message-ID: <20180921063103.GD20006@makrotopia.org>
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Hi Pavel,

On Fri, Sep 21, 2018 at 12:04:49AM +0200, Pavel Machek wrote:
> Hi!
> 
> > > > +#ifdef CONFIG_ATA_LEDS
> > > > +	/* register LED triggers for all ports */
> > > > +	for (i = 0; i < host->n_ports; i++) {
> > > > +		if (unlikely(!host->ports[i]->ledtrig))
> > > > +			continue;
> > > > +
> > > > +		snprintf(host->ports[i]->ledtrig_name,
> > > > +			sizeof(host->ports[i]->ledtrig_name), "ata%u",
> > > > +			host->ports[i]->print_id);
> > > 
> > > > +		host->ports[i]->ledtrig->name = host->ports[i]->ledtrig_name;
> > > > +
> > > > +		if (led_trigger_register(host->ports[i]->ledtrig)) {
> > > > +			kfree(host->ports[i]->ledtrig);
> > > > +			host->ports[i]->ledtrig = NULL;
> > > > +		}
> > > > +	}
> > > > +#endif
> > > 
> > > No, we don't want you to register multiple triggers. We want one
> > > trigger, than has parameter "which port to watch". (Number of triggers
> > > is limited as by sysfs limitations).
> > 
> > Back then I implemented it that way to be able to define the
> > default trigger for each LED in device tree and "trigger-sources"
> > didn't exist yet (it was introduced for USB ports and isn't yet used
> > for anything other than that)
> 
> I see why you did it... BUt I believe we still want single trigger solution...
> 
> > However, the problem till today is also that ATA ports are often not
> > individual device-tree objects we can refer to, see for example
> > marvell,armada-370-sata which appears as one opaque controller. Ie.
> > all SATA drivers have to be converted to expose individual ports on
> > device-tree before the trigger-sources approach can be applied...
> 
> Yep, well... something to do in SATA then.
> 
> Perhaps this should also have an option for single LED for _any_ SATA activity,
> and 90% devices will be happy with that?

The whole reason for not using one of the existing disk-activity
triggers was to address individual SATA ports to individual LEDs of NAS
devices (in my case Shuttle KD20)...