linux-kernel - Re: [PATCH 2/2] iio: Add AS3935 lightning sensor support

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Message-Id: <201402010628.04324.marex@denx.de>
Date:	Sat, 1 Feb 2014 06:28:04 +0100
From:	Marek Vasut <marex@...x.de>
To:	Matt Ranostay <mranostay@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	Matt Porter <matt.porter@...aro.org>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Pantelis Antoniou <pantelis.antoniou@...il.com>,
	Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH 2/2] iio: Add AS3935 lightning sensor support

On Saturday, February 01, 2014 at 06:03:22 AM, Matt Ranostay wrote:
> Duly noted. Will be fixed in the next rev... mutexs are pointless as you
> say.. only corner case would be if you were changing gain_boost and a event
> came in at the same time. But that wouldn't harm anything except slightly
> delay the gain_boost being updated by some  x microseconds.

Please stop top-posting ;-)

btw I think you might need a mutex around the entire:

+static void calibrate_as3935(struct as3935_state *st)
+{
+       /* mask disturber interrupt bit */
+       as3935_write(st, AS3935_INT, 1 << 5);
+
+       as3935_write(st, AS3935_CALIBRATE, 0x96);
+       as3935_write(st, AS3935_TUNE_CAP, 1 << 5 | st->tune_cap);
+
+       mdelay(2);
+       as3935_write(st, AS3935_TUNE_CAP, st->tune_cap);
+}

and similar functions where you do a bunch of register accesses. This is because 
you probably want to protect them against concurent execution so the chip won't 
be confused if a user were to poke something via SYSFS twice.

Best regards,
Marek Vasut
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