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    Subject[PATCH] intel8x0m: schedule timeout before warm reset check
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    At every resume a laptop I use prints this message (at KERN_ERR level):
    ALSA sound/pci/intel8x0m.c:904: AC'97 warm reset still in progress?
    [0x2]

    The thing to note here is that 0x2 corresponds to ICH_AC97COLD. Ie, what
    seems to be happening is that the register involved indicated a warm
    reset for some time (as the ICH_AC97WARM bit was set) but by the time
    the warning is printed, and that same register is checked again, that
    bit is already cleared and only the ICH_AC97COLD bit is still set.

    It turns out a warm reset needs some time to settle, but it is currently
    checked right away. The test therefore fails the first time it is done
    and schedule_timeout_uninterruptible() will be called. Once we return
    from that jiffies is already (far) past end_time on this laptop, so we
    exit the loop, print a warning, and exit the function while the warm
    reset actually succeeded.

    One way to fix this is to call schedule_timeout_uninterruptible() at the
    start of the loop. (This might punish the "finish cold reset" case, but
    on this laptop such a cold reset apparently never happens, so I can't
    say for sure.)

    While we're at it drop the extra single tick from end_time, as it looks
    rather silly.

    Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
    ---
    The question I asked in the previous message ("snd_intel8x0m: error
    message because return value is unused?") made little sense. I probably
    got quite confused by my own efforts to debug this.

    sound/pci/intel8x0m.c | 4 ++--
    1 files changed, 2 insertions(+), 2 deletions(-)

    diff --git a/sound/pci/intel8x0m.c b/sound/pci/intel8x0m.c
    index 13cec1e..9abff7b 100644
    --- a/sound/pci/intel8x0m.c
    +++ b/sound/pci/intel8x0m.c
    @@ -894,11 +894,11 @@ static int snd_intel8x0m_ich_chip_init(struct intel8x0m *chip, int probing)
    /* finish cold or do warm reset */
    cnt |= (cnt & ICH_AC97COLD) == 0 ? ICH_AC97COLD : ICH_AC97WARM;
    iputdword(chip, ICHREG(GLOB_CNT), cnt);
    - end_time = (jiffies + (HZ / 4)) + 1;
    + end_time = jiffies + HZ / 4;
    do {
    + schedule_timeout_uninterruptible(1);
    if ((igetdword(chip, ICHREG(GLOB_CNT)) & ICH_AC97WARM) == 0)
    goto __ok;
    - schedule_timeout_uninterruptible(1);
    } while (time_after_eq(end_time, jiffies));
    snd_printk(KERN_ERR "AC'97 warm reset still in progress? [0x%x]\n",
    igetdword(chip, ICHREG(GLOB_CNT)));
    --
    1.7.4.1





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