RE: [linux-audio-user] snd-hdsp+cardbus+M6807 notebook=distortion -- FIXED!

From: Ivica Ico Bukvic (ico_at_fuse.net)
Date: 04/12/04

  • Next message: Niraj Kumar: "Re: [2.6 PATCH] ufs2_frag_map_fix : fixes wrong content reading in ufs2 code" 
    To: "'Russell King'" <rmk+lkml@arm.linux.org.uk>
Date:	Mon, 12 Apr 2004 10:40:59 -0400

    > Don't think the problem is 100% solved just yet - there's still work
    > to do.
    >
    > You haven't said which kernel version you're using to test this out
    > on; 2.6.5 contains some fixes for the CB1410 in these areas, and it
    > would be useful to know if these are working.
    >
    > So, as per my previous mail and at risk of sounding like a stuck
    > record^wCD, which kernel version are you using for this test?

    Sorry :-) Mandrake Community 10.0 using the 2.6.3 kernel with a patch to fix
    the freezing when probing for the pcmcia card on this particular notebook
    (see: http://www.muru.com/linux/amd64/).
     
    > Have you also tried only changing a limited subset of these
    > registers? The reason this is important is that just immitating
    > the working scenario out right doesn't really tell us very much.

    Tried various combinations in Windows and only using the 2 in combination
    worked. I will test further in Linux if you like when I get the chance. But
    as of right now I have a hunch that the same behavior will be observed in
    Linux as one value enables burst stuff, while the other value when changed
    also introduced distortion (micro-silence between buffers) in Windows if any
    other value was used than 0x04.

    > You should be able to tweak these while the card is playing, so
    > you could try setting them all to the "working" state, play back
    > the audio, and then try undoing each change individually.

    Will do. I did that with the latency and it still worked for the
    before-mentioned reasons but the preferred behavior would be having it at
    0xff as that is how the Win driver behaves. However, changing the latency
    on-the-fly while JACK audio server and audio is running results in corrupted
    audio and JACK needs to be restarted (this is most likely issue with the
    fact I was using JACK).

    > > 2) PREFERRED: hdsp driver needs to adjust the cardbus controller latency
    >
    > No. Drivers should not fiddle with other parts of the system they
    > don't own, and the HDSP driver does not own the cardbus controller.
    > I suspect that the CB1410 quirk needs to force the latency timer at
    > startup.

    Well, in Windows the latency on the controller is 0x20 and then when the
    cardbus soundcard (RME) is inserted it is changed into 0xFF. Matthias, the
    support guy from RME also confirmed this behavior (that their driver is
    changing the value upon connection).
     
    > > 3) FOR FURTHER INVESTIGATION: Does linux hdsp driver force the f0 value
    > upon
    > > the 0x81 register or is it that in Linux one simply cannot select d0
    > value
    > > for whatever reason
    >
    > I suspect it may be caused by using a byte access to a longword-sized
    > register. 0x81 is supposed to be accessed via:
    >
    > setpci -s a.0 0x80.l
    >
    > which of course means its bits 8 to 15.

    Sounds like that was most likely it. I will test it as soon as I get the
    chance to do so.

    Thank you very much for all your help!

    Best wishes,

    Ico

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