linux-kernel - Re: [PATCH 3/3] iio: st_sensors: Use level interrupts

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Message-ID: <CACRpkda-WWO3qcyOWUNkjnheGnJA=Op4SsmorDjJmvF3=9CLcg@mail.gmail.com>
Date:	Mon, 20 Jun 2016 15:26:47 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Crestez Dan Leonard <leonard.crestez@...el.com>
Cc:	Jonathan Cameron <jic23@...nel.org>,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald-Stadler <pmeerw@...erw.net>,
	Daniel Baluta <daniel.baluta@...el.com>,
	Giuseppe Barba <giuseppe.barba@...com>,
	Denis Ciocca <denis.ciocca@...com>
Subject: Re: [PATCH 3/3] iio: st_sensors: Use level interrupts

On Fri, May 13, 2016 at 8:43 PM, Crestez Dan Leonard
<leonard.crestez@...el.com> wrote:

> As far as I can tell DRDY for ST sensors behaves as a level rather than
> edge interrupt. Registering for IRQF_TRIGGER_RISING instead of
> IRQF_TRIGGER_HIGH mostly works except when the sampling frequency is
> high enough that new samples come before the new ones are read
> completely. In that case the interrupt line remains high, no more rising
> edges occur and the iio buffer stalls.
>
> Configuring the interrupt as IRQF_TRIGGER_HIGH makes it work as
> expected. This patch makes it so that st_sensors_trigger interrupt
> request code doesn't mangle the request flags into IRQF_TRIGGER_RISING.
>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Cc: Giuseppe Barba <giuseppe.barba@...com>
> Cc: Denis Ciocca <denis.ciocca@...com>
> Signed-off-by: Crestez Dan Leonard <leonard.crestez@...el.com>
> ---
> This is an alternative fix to this patch:
>         https://www.spinics.net/lists/linux-iio/msg24722.html
> [PATCH 2/2 v6] iio: st_sensors: read surplus samples in trigger.

I have incorporated this approach into my patch now: please give
it a spin!

Yours,
Linus Walleij