From mboxrd@z Thu Jan  1 00:00:00 1970
From: Clemens Ladisch <clemens@ladisch.de>
Subject: Re: [RFC] [PATCH 02/62] mpu401:snd_mpu401_uart_new():
 split semantic of irq_flags
Date: Thu, 08 Sep 2011 22:27:43 +0200
Message-ID: <4E69253F.3090705@ladisch.de>
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To: Yong Zhang <yong.zhang0@gmail.com>
Cc: alsa-devel@alsa-project.org, Ondrej Zary <linux@rainbow-software.org>, Dan Carpenter <error27@gmail.com>, Takashi Iwai <tiwai@suse.de>, Jiri Kosina <jkosina@suse.cz>, linux-kernel@vger.kernel.org, Andreas Mohr <andi@lisas.de>, Lucas De Marchi <lucas.demarchi@profusion.mobi>, Julia Lawall <julia@diku.dk>, =?UTF-8?B?VXdlIEtsZWluZS1Lw7ZuaWc=?= <u.kleine-koenig@pengutronix.de>, Joe Perches <joe@perches.com>, tglx@linutronix.de, mingo@elte.hu
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Yong Zhang wrote:
> On Thu, Sep 08, 2011 at 03:58:45PM +0200, Clemens Ladisch wrote:
> > ...
> > Here, "no interrupt" and "already reserved" actually mean the same thing,
> > i.e., that the interrupt handling is the responsibility of some other
> > driver.

Sorry, after checking the code, I've realized that my description was
wrong.  irq_flags==0 ("already reserved") means that snd_mpu401_uart_new
should not try to allocate the interrupt, while irq==-1 ("no interrupt")
means that the device never issues mpu401 interrupts, so that the mpu401
code must use a timer to poll the device.

I'll write a patch that changes this function so that irq<0 means
"already reserved", and that "no interrupt" gets another bit in the
info_flags parameter.


Regards,
Clemens