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