ALSA MIDI serial u16550 horribly broken in 2.6.4

ALSA MIDI serial u16550 horribly broken in 2.6.4

[Dave Jones]

poking io port 0x1 probably isn't going to do much good.
Here's what happens after a 'modprobe snd_serial_u16550'

		Dave

u16550: can't grab port 0x1
no UART detected at 0x1
Unable to handle kernel NULL pointer dereference at virtual address 00000020
 printing eip:
c788b38f
*pde = 00000000
Oops: 0000 [#1]
SMP
CPU:    0
EIP:    0060:[<c788b38f>]    Not tainted
EFLAGS: 00010246   (2.6.4-prep)
EIP is at snd_info_unregister+0x5/0x60 [snd]
eax: 00000000   ebx: c1286b1c   ecx: 00000000   edx: 00000000
esi: 00000000   edi: c1286b59   ebp: c1286b40   esp: c21cef4c
ds: 007b   es: 007b   ss: 0068
Process modprobe (pid: 8679, threadinfo=c21ce000 task=c37a0ce0)
Stack: c1286b1c fffffff0 c1286b59 c7889c6d 00000000 c78991f6 c1286b59 c1286b40
       c78073f3 00009600 0001c200 00000000 00000000 c7807490 c1286b1c 00000000
       00000000 00000000 c031bbd8 c21ce000 c78074b4 c031bbf8 c789ac00 c0138fad
Call Trace:
 [<c7889c6d>] snd_card_free+0x163/0x1ed [snd]
 [<c78073f3>] snd_serial_probe+0x12a/0x1de [snd_serial_u16550]
 [<c7807490>] snd_serial_probe+0x1c7/0x1de [snd_serial_u16550]
 [<c78074b4>] alsa_card_serial_init+0xd/0x34 [snd_serial_u16550]
 [<c0138fad>] sys_init_module+0x14f/0x25f
 [<c02c4567>] syscall_call+0x7/0xb
 
Code: 8b 40 20 85 c0 74 05 8b 78 34 eb 06 8b 3d 2c 5f 89 c7 bb 90

Re: ALSA MIDI serial u16550 horribly broken in 2.6.4

[Jaroslav Kysela]

On Mon, 15 Mar 2004, Dave Jones wrote:

> poking io port 0x1 probably isn't going to do much good.
> Here's what happens after a 'modprobe snd_serial_u16550'

Thanks. I've fixed this problem in our CVS tree. The oops should
be fixed in the current Linus's tree, too.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs

Re: ALSA MIDI serial u16550 horribly broken in 2.6.4

[Dave Jones]

On Mon, Mar 15, 2004 at 05:29:44PM +0100, Jaroslav Kysela wrote:
 > On Mon, 15 Mar 2004, Dave Jones wrote:
 > 
 > > poking io port 0x1 probably isn't going to do much good.
 > > Here's what happens after a 'modprobe snd_serial_u16550'
 > 
 > Thanks. I've fixed this problem in our CVS tree. The oops should
 > be fixed in the current Linus's tree, too.

Hmm, I don't see it at http://cvs.sourceforge.net/viewcvs.py/alsa/alsa-kernel/drivers/serial-u16550.c
Is there somewhere else I should look ?

This was pretty close to top of tree already btw, (only missing
the csets from a few hours ago). I'll test again shortly with top-of-tree.

		Dave

Re: ALSA MIDI serial u16550 horribly broken in 2.6.4

[Takashi Iwai]

[-- Attachment #1: Type: text/plain, Size: 676 bytes --]

At Mon, 15 Mar 2004 17:51:10 +0000,
Dave Jones wrote:
> 
> On Mon, Mar 15, 2004 at 05:29:44PM +0100, Jaroslav Kysela wrote:
>  > On Mon, 15 Mar 2004, Dave Jones wrote:
>  > 
>  > > poking io port 0x1 probably isn't going to do much good.
>  > > Here's what happens after a 'modprobe snd_serial_u16550'
>  > 
>  > Thanks. I've fixed this problem in our CVS tree. The oops should
>  > be fixed in the current Linus's tree, too.
> 
> Hmm, I don't see it at http://cvs.sourceforge.net/viewcvs.py/alsa/alsa-kernel/drivers/serial-u16550.c
> Is there somewhere else I should look ?

it must be the usual delay of sourceforce's anon cvs tree...
the patch is attached below.


Takashi

[-- Attachment #2: Type: text/plain, Size: 673 bytes --]

--- linux/sound/drivers/serial-u16550.c	13 Jan 2004 17:09:57 -0000	1.20
+++ linux/sound/drivers/serial-u16550.c	15 Mar 2004 17:40:01 -0000	1.21
@@ -342,7 +342,7 @@
 	unsigned char c;
 
 	/* Do some vague tests for the presence of the uart */
-	if (io_base == 0) {
+	if (io_base == 0 || io_base == SNDRV_AUTO_PORT) {
 		return -ENODEV;	/* Not configured */
 	}
 
@@ -804,10 +804,9 @@
 		return err;
 	}
 
-	if (irq >= 0) {
+	if (irq >= 0 && irq != SNDRV_AUTO_IRQ) {
 		if (request_irq(irq, snd_uart16550_interrupt,
 				SA_INTERRUPT, "Serial MIDI", (void *) uart)) {
-			uart->irq = -1;
 			snd_printk("irq %d busy. Using Polling.\n", irq);
 		} else {
 			uart->irq = irq;