[alsa-devel] [RFC] [PATCH 02/62] mpu401:snd_mpu401_uart_new(): split semantic of irq_flags

Yong Zhang yong.zhang0 at gmail.com
Wed Sep 14 10:49:57 CEST 2011

On Tue, Sep 13, 2011 at 11:24:41AM +0200, Clemens Ladisch wrote:
> completely untested:
> --8<---------------------------------------------------------------->8--
> ALSA: mpu401: clean up interrupt specification
> The semantics of snd_mpu401_uart_new()'s interrupt parameters are
> somewhat counterintuitive:  To prevent the function from allocating its
> own interrupt, either the irq number must be invalid, or the irq_flags
> parameter must be zero.  At the same time, the irq parameter being
> invalid specifies that the mpu401 code has to work without an interrupt
> allocated by the caller.  This implies that, if there is an interrupt
> and it is allocated by the caller, the irq parameter must be set to
> a valid-looking number which then isn't actually used.
> With the removal of IRQF_DISABLED, zero becomes a valid irq_flags value,
> which forces us to handle the parameters differently.
> This patch introduces a new flag MPU401_INFO_IRQ_HOOK for when the
> device interrupt is handled by the caller, and makes the allocation of
> the interrupt to depend only on the irq parameter.  As suggested by
> Takashi, the irq_flags parameter was dropped because, when used, it had
> the constant value IRQF_DISABLED.

Thanks Clemens. Your patch will eventually save much lines from mine ,
actually I only need to touch request_irq() in snd_mpu401_uart_new().

But do you have any idea by which tree this patch will go to mainline?
Thus I could make a new patch based on it :)

> Signed-off-by: Clemens Ladisch <clemens at ladisch.de>

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