[alsa-devel] Could you help me about the ALSA?

[l9jj at 163.com]

>> 
>>  
>> 
>> Yes,when buffer_size wraped the 'pos' is smallar than last one.If we
>> want to confirm the hw_base need to adjust there must be consider
>> another confidition:
>> 
>> hdelta = jiffies - runtime->hw_ptr_jiffies;
>> 
>>               if (hdelta > runtime->hw_ptr_buffer_jiffies/2)
>> 
>> how to connect this code with checking unnormal interrupt(lost or delayed)?
>
>This condition is for the double interrupt acknowledge problems (see
>comment). It makes sure, that the DMA buffer position was wrapped using
>another external timing source. Indeed, it's mostly a lowlevel driver
>fault to call this pointer update routine with the in_interrupt flag
>when the period was not really elapsed.
>

But,why alsa use the specific  value 'runtime->hw_ptr_buffer_jiffies/2' to compare with hdelta than other?