Thanks for the reply.
Actually I know where the problem in my code is: inside the put callback
(see below) I am calling a function (dsp_setoutput) that is sending the
signal to the DSP, there I wanted to wait for the reply of the DSP to
get a feedback whether the request was successful or not. This was done
by a semaphore (going down and waiting for IRQ from DSP that is setting
sema up), and thats the point where the posted bug occured.
So I was just wondering that it seems that there is no possibility to
wait for a reply of the DSP, to be sure that a given value has been set?
(for the interested ones, here is the code..)
static int snd_mychip_output_set_put(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_value *ucontrol)
{
struct snd_mychip *mychip = snd_kcontrol_chip(kcontrol);
int addr = kcontrol->private_value;
short change = 0;
spin_lock_irq(&mychip->mixer_lock);
if (ucontrol->value.integer.value[0] != mychip->output_set[addr]) {
if (dsp_setoutput(addr+1, ucontrol->value.integer.value[0]) >= 0)
{
mychip->output_set[addr] = ucontrol->value.integer.value[0];
change = 1;
}
else // error sending signal
{
change = -EBUSY; // device or resource busy
}
}
spin_unlock_irq(&mychip->mixer_lock);
return change;
}
later on in the called function...
// wait for reply via semaphore
while(!end)
{
if (down_interruptible(&dsp_reply_sema)==-EINTR) // HERE WE GET
BUG: scheduling while atomic: amixer/0x00000001/430 ...
// waked by signal (terminate), leave thread
printk(INFO "reply: catched signal\n");
end=1;
break;
}
printk(INFO "dsp_reply signaled (saved status =
%i)\n",stDspReply.status);
end=1;
...
}
Another point: I figured out that the "ALSA middlelayer" seems to filter
the given values of a control. So if the user sets value=1000 where
maximum is 10, I will get 10 instead of 1000 in the put callback...so
it's not necessary to check values in those callbacks, but unfortunately
that's not always good - because sometimes it doesn't make sense to use
the max or min values if the user just entered a wrong number...
thanks so far
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