On Thu, 22 Aug 2002, Shaju Abraham wrote:
> Hi all,
>
> In our study that we are doing abt latency of sound cards, we want
> to have a situation where I do not want to use all of the 32 bds
> available. we want to use say only 4 or 8 of the bds with each bd
> pointing to only a small fragment of data.( This is basically to make
> the card interrupt frequently and will also should not be able to
> proceed if the interrupts raised by the past bds have not been serviced.
> So want to restrict it to 4 or 8 ) .
>
> It will be of great help if you can help us on the following two points.
>
> i) What is the significance of ICH_MAX_FRAGS? ( It seems
> to be used only for the allocation of pages for the buffer and for
> little else during the actual functioning of the card.)
>
> ii) What is the significance of ICH_REG_LVI_MASK? (This
> is more used during the actual functioning of the card & is used in the
> interrupt service sub-routine to update the lvi.) It is by default 0x1f
> . Is this 'cos it can be used to address the 32 bds available. I
> changed this to 3 and 7 . I observed that this makes the card to use
> only 4 or 8 of the bds available. Am I correct in this conclusion? If I
> do this, I get some noise. Is this because of the interrupts raised by
> the unused bds?
>
> If I am wrong abt all this, how should I go abt my idea of using
> only 4 or 8 of the bds available?
I'm rewriting the intel8x0 driver to use scatter-gather DMA access and
adding support for I845. So these question will be obsolete after a few days.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project http://www.alsa-project.org
SuSE Linux http://www.suse.com
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