On Sun, 2009-01-04 at 12:37 +0100, Gregoire Favre wrote:
> Hello,
>
> in order to use S2API I compiled s2-lipliandvb with attached config and
> it ended with an oops which make me loose my USB keyboard...
>
> What can I do in order to help this being fixed ?
The oops shows a failure happens in
linux/drivers/media/video/cx88/cx88-vp3054-i2c.c:vp3054_i2c_probe()
Which in the source code I have lying around looks like:
int vp3054_i2c_probe(struct cx8802_dev *dev)
{
struct cx88_core *core = dev->core;
struct vp3054_i2c_state *vp3054_i2c;
int rc;
if (core->boardnr != CX88_BOARD_DNTV_LIVE_DVB_T_PRO)
return 0;
[...]
But the disassembed code in your oops doesn't quite match this source.
I can tell you this about the oops:
Code; ffffffffa088f12f <_end+200a7ebf/7ee18d90>
0000000000000000 <_RIP>:
Code; ffffffffa088f12f <_end+200a7ebf/7ee18d90>
0: a0 df 66 66 66 66 66 mov 0x2e666666666666df,%al
Code; ffffffffa088f136 <_end+200a7ec6/7ee18d90>
7: 66 2e
Code; ffffffffa088f138 <_end+200a7ec8/7ee18d90>
9: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
Code; ffffffffa088f13f <_end+200a7ecf/7ee18d90>
10: 00
Code; ffffffffa088f140 <_end+200a7ed0/7ee18d90>
11: 48 83 ec 28 sub $0x28,%rsp
Code; ffffffffa088f144 <_end+200a7ed4/7ee18d90>
15: 48 89 5c 24 08 mov %rbx,0x8(%rsp)
Code; ffffffffa088f149 <_end+200a7ed9/7ee18d90>
1a: 48 89 6c 24 10 mov %rbp,0x10(%rsp)
Code; ffffffffa088f14e <_end+200a7ede/7ee18d90>
1f: 4c 89 64 24 18 mov %r12,0x18(%rsp)
Code; ffffffffa088f153 <_end+200a7ee3/7ee18d90>
24: 4c 89 6c 24 20 mov %r13,0x20(%rsp)
Code; ffffffffa088f158 <_end+200a7ee8/7ee18d90>
29: 31 db xor %ebx,%ebx
Code; ffffffffa088f15a <_end+200a7eea/7ee18d90> <=====
2b: 4c 8b 27 mov (%rdi),%r12 <=====
Code; ffffffffa088f15d <_end+200a7eed/7ee18d90>
2e: 48 89 fd mov %rdi,%rbp
Code; ffffffffa088f160 <_end+200a7ef0/7ee18d90>
31: 41 83 bc 24 c0 06 00 cmpl $0x2a,0x6c0(%r12)
^^^^^
This comparison -------------------------|
corresponds to
if (core->boardnr != CX88_BOARD_DNTV_LIVE_DVB_T_PRO)
as 0x2a equals 42 and
#define CX88_BOARD_DNTV_LIVE_DVB_T_PRO 42
Since that's the case, %r12 would hold the "core" pointer. Since "core"
is fetched from wherever %rdi points %rdi should be "dev". Since the
oops happens when %rdi is dereferenced "dev" was equal to NULL.
So linux/drivers/media/video/cx88/cx88-dvb.c:cx8802_dvb_probe() called
vp3054_i2c_probe() with "dev" equla to NULL. Looking at that function:
static int cx8802_dvb_probe(struct cx8802_driver *drv)
{
struct cx88_core *core = drv->core;
struct cx8802_dev *dev = drv->core->dvbdev;
int err;
dprintk( 1, "%s\n", __func__);
dprintk( 1, " ->being probed by Card=%d Name=%s, PCI %02x:%02x\n",
core->boardnr,
core->name,
core->pci_bus,
core->pci_slot);
err = -ENODEV;
if (!(core->board.mpeg & CX88_MPEG_DVB))
goto fail_core;
/* If vp3054 isn't enabled, a stub will just return 0 */
err = vp3054_i2c_probe(dev);
[...]
drv->core->dvbdev must have been NULL, even though the check against
CX88_MPEG_DVB succeeded.
Backing up and looking at
linux/drivers/media/video/cx88/cx88-mpeg.c:cx8802_register_driver()
which is what registers the cx8802_dvb_probe() and calls it for each
device, core->dvbdev is never explicitly set.
Backing up even further
linux/drivers/media/video/cx88/cx88-dvb.c:dvb_init() never sets it
either.
So it must be the case, that dvbdev must be set to NULL, in a device in
the cx8802_devlist, when the cx88-dvb module is loaded.
I note that in
linux/drivers/media/video/cx88/cx88-mpeg.c:cx8802_probe()
the cx8802 based device is added to the cx8802_devlist before the dvbdev
is set to something non-NULL. Then a request to load modules happens.
That's probably OK for a single cx8802 device in a machine, but I think
it's a race condition if you have more than one of these cx8802 devices
in a machine.
I hope that helps someone. I'm not and expert on the cx88 modules and
their inter-relationships.
Regards,
Andy
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