No subject

[Uwe Kleine-König]

<jason77.wang at gmail.com>
Bcc: 
Subject: Re: i.MX & IRQF_ONESHOT
Reply-To: 
In-Reply-To: <4D2EB6EF.7030608 at eukrea.com>

Hello,

[adding tglx who AFAIK invented threaded irqs and the people involved
in 2991a1ca6e9b to Cc]

On Thu, Jan 13, 2011 at 09:25:19AM +0100, Eric Bénard wrote:
> while testing 2.6.37 on our i.MX27 based board - code in
> arch/arm/mach-imx/eukrea_mbimx27-baseboard.c - I noticed the
> touchscreen controller (ADS7846) doesn't work anymore.
> 
> A few IRQ are generated when probing for the chipset and starting
> calibration (usually first point works), then nothing more (even if
> the IRQ signals is generated as seen on the scope, the irq count
> doesn't increase anymore and stays <= 4 and no data is reported to
> the input layer).
> 
> drivers/input/touchscreen/ads7846.c was switched to threaded IRQ in
> commit 2991a1ca6e9b13b639a82c0eec0cbc191bf1f42f where was added :
> irq_flags |= IRQF_ONESHOT;
AFAIK this is how threaded irq usually work.  The irq should get
reenabled by irq_thread -> irq_finalize_oneshot then.

> Commenting out this line in the ads7846 driver makes it work again.
> Am I missing something obvious or is there a reason for IRQF_ONESHOT
> creating trouble with gpio irq or SPI on i.MX ?
I don't know.  Is the irq masked?  pending?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |