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authorPaul Bolle <pebolle@tiscali.nl>2011-03-11 11:24:52 +0100
committerTakashi Iwai <tiwai@suse.de>2011-03-11 15:22:00 +0100
commit5cd2ad81f912c8535491f541108b655f4552dff9 (patch)
tree3dc74dc647e858967a33c777af91ee65e1dc6ac8
parent88a8516a2128a6d078a106ead48092240e8a138f (diff)
downloadlinux-5cd2ad81f912c8535491f541108b655f4552dff9.tar.bz2
ALSA: intel8x0m: wait a bit before warm reset check
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. A way to fix this is to call usleep_range() after writing to the register involved. A handful of tests suggest 500 usecs is a safe value. (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> Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/pci/intel8x0m.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/sound/pci/intel8x0m.c b/sound/pci/intel8x0m.c
index 13cec1e5ced9..b1c926cd281b 100644
--- a/sound/pci/intel8x0m.c
+++ b/sound/pci/intel8x0m.c
@@ -894,7 +894,8 @@ 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;
+ usleep_range(500, 1000); /* give warm reset some time */
+ end_time = jiffies + HZ / 4;
do {
if ((igetdword(chip, ICHREG(GLOB_CNT)) & ICH_AC97WARM) == 0)
goto __ok;