some bits about cirrus 46xx: from LKML

["Andrea Venturi (personale)" <andrea.venturi@tin.it>]

FYI: i didn't see this email on ALSA-DEVEL, so i'm posting here too..

don't know if useful to anyone.. but it's a real pity to see the cirrus 
dsp couldn't be exploited to its "real" power by lack of a single cirrus 
people! :-(

bye

andrea venturi

================================

From: "Woller, Thomas" <tom.woller@cirrus.com>
To: "'David Ford'" <david+cert@blue-labs.org>,
    "Woller, Thomas" <tom.woller@cirrus.com>,
    linux-kernel <linux-kernel@vger.kernel.org>
Subject: RE: 2.4.3+ sound distortion
Date: 	Wed, 6 Mar 2002 10:43:53 -0600

david, et al
a) i am very sorry about the tinny sound you are experiencing. we
no longer have any DSP pc audio engineers working at cirrus, and
pc audio products are no longer developed or supported here at
cirrus. i have talked this problem over with the only person that
might help, and the debugging effort involved is extensive and
may not yield results.  we do not fully understand the issue, but
believe that several internal points in the DSP become misaligned
resulting in the tinny sound.
b) the static DSP image that is currently used with the linux
cs46xx driver, is not capable of any of the fancy extensive
feature set, and the work involved would require an engineer with
intimate knowledge of the DSP which no longer is present.
c)see b
d) i am always willing to assist the linux effort, it's just
difficult due to the lack of any support at cirrus for pc audio
any longer.  i am working on embedded RTOS in my official job,
but always try to fix any linux pc audio related bugs as i am
able. also, without any DSP engineers we can not create another
static DSP image with the additional tasks necessary to take
advantage of the wonderful features of cards with the cs46xx
controller. we are stuck with the current DSP images that are
available.

there is a small glimmer of light concerning secondary codec
support and SPDIF support.  i had found 2 other "test" static DSP
images that might be useful.
i placed 2 piles of code out on a cirrus ftp site (see below).
the first is a cs46xx driver with an untested static DSP image
that snoops the data to the primary codec and pumps it to the
secondary, so that there is sound coming from the rear speakers,
although the same as the the front.
the second pile of code (EOLT) contains a set of tests that we
used for testing the cs4630.  the static image used in these
tests contained in this directory functioned with SPDIF in/out. i
am unsure whether the other tasks are loaded in this image to
support the general audio data paths, so this static image may
not support more than spdif.  i tried using the static "spdif"
image on the latest cs46xx linux driver, but it did not work with
a simple static image replacement in the source. specific problem
definition and resolution using the spdif EOLT static image with
the linux cs46xx sources, has not been determined.  anyone and
everyone are welcome to look over these 2 piles of source, but my
time is very limited concerning any new development for spdif
and/or secondary codec.
here is the ftp site info. the cs46xx code is based on an older
version of the 2.4 kernel.

server: ftp1.cirrus.com
login: ftppclink
password: cSPxQMd

thanks
Tom Woller




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