When the Linux kernel is compiled with CONFIG_DEBUG_SHIRQ=y,
the Soundblaster Audigy2 ZS Notebook PCMCIA card causes the
system hang during boot (udev stage) or when the card is hot-plug.
The CONFIG_DEBUG_SHIRQ flag is by default 'y' with all Fedora
kernels since 2.6.23. The problem was reported as
https://bugzilla.redhat.com/show_bug.cgi?id=326411
The issue was hunted down to the snd_emu10k1_create() routine:
/* pseudo-code */
snd_emu10k1_create(...) {
...
request_irq(... IRQF_SHARED ...) {
register the irq handler
#ifdef CONFIG_DEBUG_SHIRQ
call the irq handler: snd_emu10k1_interrupt() {
poll I/O port // <---- !! system hangs
...
}
#endif
}
...
snd_emu10k1_cardbus_init(...) {
initialize I/O ports
}
...
}
The early access to I/O port in the interrupt handler causes
the freeze. Obviously it is necessary to init the I/O ports
before accessing them. This patch moves the registration of
the irq handler after the initialization of the I/O ports.
Signed-off-by: Jaroslav Franek <jarin.franek@post.cz>
Acked-by: James Courtier-Dutton <James@superbug.co.uk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
868e15dbd2