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From: Pavel Machek <pavel@ucw.cz>
To: Oleh Kravchenko <oleg@kaa.org.ua>
Cc: linux-leds@vger.kernel.org
Subject: Re: [PATCH] leds: add LED driver for CR0014114 board
Date: Sat, 12 Aug 2017 21:13:00 +0200	[thread overview]
Message-ID: <20170812191300.GA23619@amd> (raw)
In-Reply-To: <00efd6b5-494f-0f8d-d32b-321236ed8aaa@kaa.org.ua>

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Hi!

> > Hmm. Well, this works if you can't provide better names. Still "board"
> > is somehow generic, andsomeone else might want to use it. "board" ->
> > "crms"?
> 
> It's specified in device tree by defining label.
> In my examples:
> board@0 {
>        compatible = "ccs,cr0014114";
>        reg = <0>;
>        spi-max-frequency = <50000>;
>        spi-cpha;
>        label = "board0";
> };
> 
> board@1 {
>        compatible = "ccs,cr0014114";
>        reg = <1>;
>        spi-max-frequency = <50000>;
>        spi-cpha;
>        label = "board1";
> };

Ok, makes sense. How does the board look?

> >>>>>> +	while (i--)
> >>>>>> +		led_classdev_unregister(&priv->leds[i].ldev);
> >>>>>
> >>>>> Can devm_* be used to simplify this?
> >>>>
> >>>> I think no, because it will cause race condition.
> >>>
> >>> Please take a look at devm_led_classdev_register() and friends. It
> >>> should be possible to simplify code without races.
> >>
> >> I don't understand how I can call destroy_workqueue() after calling unregister leds.
> > 
> > Do you actually need the workqueues? It should be possible to avoid
> > them, using workqueue support in the core.
> 
> The delay between data sends to SPI board should be at least 10 ms
> I think it will be bad idea to use shared workqueue from kernel,
> so I create separate single threaded work queue :)

If workqueue support in led core can not take 10 msec wait, we should
fix it, not add hacks around...
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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  reply	other threads:[~2017-08-12 19:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-12  9:09 [PATCH] leds: add LED driver for CR0014114 board Oleh Kravchenko
2017-08-12  9:30 ` Pavel Machek
2017-08-12 10:28   ` Oleh Kravchenko
2017-08-12 10:56     ` Pavel Machek
2017-08-12 11:34       ` Oleh Kravchenko
2017-08-12 17:46         ` Pavel Machek
2017-08-12 18:50           ` Oleh Kravchenko
2017-08-12 19:13             ` Pavel Machek [this message]
2017-08-12 19:39               ` Oleh Kravchenko
2017-09-28 15:24                 ` Pavel Machek

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