Re: ALSA Memory Allocation Bug

[Takashi Iwai <tiwai@suse.de>]

At Wed, 12 May 2004 18:40:05 -0700,
Loc Ho wrote:
> 
> Hi,
> 
> I developed an custom USB Audio driver. In addition, I am also using
> the provided USB Audio driver for commercial USB Audio devices. After
> some testing with the custom USB Audio driver and the provided USB
> Audio driver, there seem to be a problem with the ALSA memory
> allocation routine. In file pcm_memory.c function setup_pcm_id, the id
> is generated using the pcm device ID, stream ID, and substream
> number. This only guarantee that the memory tag ID is unique for one
> card. If I have multiple cards, they will not be unique. Am I correct?

no, usually you have a unique struct device pointer for each card, so
it's no problem.  the tag is a pair of device pointer and id number.

however, if the same struct device is shared among multiple card
instances, you'll need to set up the id field by yourself.  an
exmample is found in mixart driver.


Takashi


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