At Wed, 19 Aug 2009 18:22:19 +0800,
Shine Liu wrote:
>
> There's no restriction on that the runtime->period_size should be the
> multiplicator of the runtime->buffer_size in current kernel code.
>
> So "hw_ptr_interrupt = runtime->hw_ptr_interrupt +
> runtime->period_size;" is not always the trueth.
The hw_ptr_interrupt is the expected position where the current irq is
issued. So, the current code should be correct -- it's simply
increased in the size of period_size.
> I've encounter the problem of this bug, the kernel told me "PCM:
> Unexpected hw_pointer value (stream=0, pos=8, intr_ptr=16384)".
>
> The period_size and buffer_size I used was 0x800 and 0x3e80 when the bug
> occured.
>
> Following patch will fix the bug.
Does the problem happen with the latest driver code (as found in
sound git tree or alsa-driver-snapshot)? If yes, we'd need more
further analysis, e.g. by enabling some xrun_debug flags.
thanks,
Takashi
> Signed-off-by: Shine Liu <shinel@xxxxxxxxxxx>
> -----------------------------------------------------------------------
>
> --- a/sound/core/pcm_lib.c 2009-08-14 06:43:34.000000000 +0800
> +++ b/sound/core/pcm_lib.c 2009-08-19 17:59:00.000000000 +0800
> @@ -248,6 +248,12 @@
> hw_base = runtime->hw_ptr_base;
> new_hw_ptr = hw_base + pos;
> hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;
> + /* if the period_size is not the multiplicator of the
> + * buffer_size, the hw_ptr_interrupt calculated above
> + * may not be correct, should be fixed.
> + */
> + if(hw_ptr_interrupt > hw_base + runtime->buffer_size)
> + hw_ptr_interrupt = hw_base + runtime->buffer_size;
> delta = new_hw_ptr - hw_ptr_interrupt;
> if (hw_ptr_interrupt >= runtime->boundary) {
> hw_ptr_interrupt -= runtime->boundary;
>
>
>
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