Messages in this thread Patch in this message | | | Date | Sun, 27 Feb 2011 10:04:55 +0100 | From | Takashi Iwai <> | Subject | Re: [PATCH] intel8x0m: schedule timeout before warm reset check |
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At Sun, 27 Feb 2011 01:23:58 +0100, Paul Bolle wrote: > > 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.
It'd be better to put a more proper delay time than tick, e.g. usleep_range() or whatever. schedule_timeout(1) can be a different length depending on HZ.
Could you figure out?
thanks,
Takashi
> > 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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