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