Re: emu10k1x/AudigyLS period table

[Takashi Iwai <tiwai@suse.de>]

At Mon, 28 Jun 2004 22:49:43 -0400,
fmoraes@nc.rr.com wrote:
> 
> This the information that James Courtier-Dutton found about the AudigyLS that also works for the emu10k1x:
> 
> #define PLAYBACK_LIST_ADDR	0x00		/* Base DMA address of a list of pointers to each period/size */
> 						/* One list entry: 4 bytes for DMA address, 
> 						 * 4 bytes for period_size << 16.
> 						 * One list entry is 8 bytes long.
> 						 * One list entry for each period in the buffer.
> 						 */
> #define PLAYBACK_LIST_SIZE	0x01		/* Size of list in bytes << 16. E.g. 8 periods -> 0x00380000  */
> #define PLAYBACK_LIST_PTR	0x02		/* Pointer to the current period being played */
> 
> Is this in anyway similar to the emu10k1 PTB scatter-gather? Just wondering if they reused the design.

No, it looks rather similar with the buffer descriptors used in
via82xx or intel8x0 to me.  You can take a look at via82xx code for
supporting SG-buffer.  It's a bit complicated because the period size
isn't always aligned to the page size.


Takashi


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