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.
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.
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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