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

Yong Zhang
2011-09-14T08:55:28Z

On Tue, Sep 13, 2011 at 11:24:41AM +0200, Clemens Ladisch wrote:
[snip]
>
> 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 :)

Thanks,
Yong
>
> Signed-off-by: Clemens Ladisch <clemens@ladisch.de>