Re: Linux 2.5.4 Sound Driver Problem

[John Weber <weber@nyc.rr.com>]

Alan Cox wrote:
>>>The sound_alloc_dmap() function in dmabuf.c must be changed from using 
>>>__get_free_pages() and virt_to_bus() -> pci_alloc_consistent().
>>>
>>What the hell are you talking about, I changed it long ago.
>>Linus uses ymfpci on his Crusoe Picturebook with no problems.
>>What is your kernel version?
>>
> 
> In the ymfpci case its not the sound_alloc_dmap (at least not in 2.4 but
> 2.5 might be out of date except in -dj). Its the use of virt_to_bus still
> rather than the handles returned from the pci api
> 
> 

I am looking at both 2.5.4 and 2.4.18-pre9.

In my copy of sound_alloc_dmap(), I see a direct call to 
__get_free_pages to allocate the buffer and a call to virt_to_bus.  I 
just thought that this could be cleared up by using pci_alloc_consistent 
(since this function will call __get_free_pages anyway and eliminates 
the need to use virt_to_bus).

Anyway, I'm not sure I understand this.  I know using the virt_to_bus is 
wrong, but why would we use __get_free_pages() here?  (This is not a 
rhetorical question, I honestly want to learn).