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Date: Tue, 04 Dec 2001 18:09:10 -0500
From: Doug Ledford <dledford@redhat.com>
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To: Nathan Bryant <nbryant@optonline.net>
CC: Mario Mikocevic <mozgy@hinet.hr>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: i810 audio patch
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Nathan Bryant wrote:

> Nathan Bryant wrote:
> 
>> this may be due to an output underrun... or i suppose lost interrupt 
>> is also possible.
>>
>> i think it might be wise to use 
>> get_available_read_data/get_free_write_space from i810_poll instead of 
>> dmabuf->count directly. i'll try this and see if it works... 
> 
> 
> No good. I tried the following, thinking that the underrun handling in 
> get_free_write_space would help, but it does the same thing.
> 
> What interrupt do we get upon underrun, are we dropping the 
> dmabuf->enable or DAC_RUNNING state when that happens?


Yes, on underrun the DAC is stopped and dmabuf->enable is cleared. 
That's clearly a bug in this case.  However, it should only cause your 
problem if you are in fact getting an underrun.  Anyway, here's a 
proposed fix you can try to see if that's what's causing the problem:


> -- 
> 
> static unsigned int i810_poll(struct file *file, struct 
> poll_table_struct *wait){
>        struct i810_state *state = (struct i810_state *)file->private_data;
>        struct dmabuf *dmabuf = &state->dmabuf;
>        unsigned long flags;
>        unsigned int mask = 0;
>        int count;
> 
>        if(!dmabuf->ready)
>                return 0;
>        poll_wait(file, &dmabuf->wait, wait);
>        spin_lock_irqsave(&state->card->lock, flags);
>        if (file->f_mode & FMODE_READ && dmabuf->enable & ADC_RUNNING) {


	if (file->f_mode & FMODE_READ && ((dmabuf->enable & ADC_RUNNING)
					 || (dmabuf->trigger &
					     PCM_ENABLE_INPUT))) {


>                count = i810_get_available_read_data(state);
>                if (count >= (signed)dmabuf->userfragsize)
>                        mask |= POLLIN | POLLRDNORM;
>        }
>        if (file->f_mode & FMODE_WRITE && dmabuf->enable & DAC_RUNNING) {


	if (file->f_mode & FMODE_WRITE &&((dmabuf->enable & DAC_RUNNING)
					|| (dmabuf->trigger &
					    PCM_ENABLE_OUTPUT))) {


>                count = i810_get_free_write_space(state);
>                if (count >= (signed)dmabuf->userfragsize)
>                        mask |= POLLOUT | POLLWRNORM;
>        }
>        spin_unlock_irqrestore(&state->card->lock, flags);
>        return mask;
> }
> 



-- 

  Doug Ledford <dledford@redhat.com>  http://people.redhat.com/dledford
       Please check my web site for aic7xxx updates/answers before
                       e-mailing me about problems

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