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