On Tue, Feb 26, 2013 at 05:39:46PM -0800, Linus Torvalds wrote:
On Mon, Feb 25, 2013 at 4:05 PM, Dave Airlie airlied@linux.ie wrote:
Highlights:
i915: all over the map, haswell power well enhancements, valleyview macro horrors cleaned up, killing lots of legacy GTT code,
Lowlight:
There's something wrong with i915 DP detection or whatever. I get stuff like this:
[ 5.710827] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not signal timeout (has irq: 1)! [ 5.720810] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not signal timeout (has irq: 1)! [ 5.730794] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not signal timeout (has irq: 1)! [ 5.740782] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not signal timeout (has irq: 1)! [ 5.750775] [drm:intel_dp_aux_wait_done] *ERROR* dp aux hw did not signal timeout (has irq: 1)! [ 5.750778] [drm:intel_dp_aux_ch] *ERROR* dp_aux_ch not done status 0xa145003f ..... [ 8.149931] [drm:intel_dp_aux_ch] *ERROR* dp_aux_ch not done status 0xa145003f
and after that the screen ends up black.
It's happened twice now, but is not 100% repeatable. It looks like the message itself is new, but the black screen is also new and does seem to happen when I get the message, so...
The second time I touched the power button, and the machine came back. Apparently the suspend/resume cycle made it all magically work: the suspend caused the same errors, but then the resume made it all good again.
Some kind of missed initialization at bootup? It's not reliable enough to bisect, but I obviously suspect commit 9ee32fea5fe8 ("drm/i915: irq-drive the dp aux communication") since that is where the message was added..
Btw, looking at that commit, what do you think the semantics of the timeout in something like
done = wait_event_timeout(dev_priv->gmbus_wait_queue, C, 10);would be? What's that magic "10"? It's some totally random number.
Guys, it should be something meaningful. If you meant a tenth of a second, use HZ/10 or something. Because just the plain "10" is crazy. I happen to have CONFIG_HZ_1000=y, and you're apparently waiting for a hundreth of a second. Was that what you intended? Because if it was, it is still crap, since CONFIG_HZ might be 100, and then you're waiting for ten times longer.
IOW, passing in a random number like that is crazy. It cannot possibly be right.
I have no idea whether the timeout has anything to do with anything, but it reinforces my suspicion that there is something wrong with that commit.
Ok, I've merged two patches from Paulo, one to fixup the harmless jiffies vs. msec confusion. And the other to plug a race in our irq handler which did lead to missed dp aux interrupts according to some digging done by Imre. The important patch is the current tip of
git://people.freedesktop.org/~danvet/drm-intel drm-intel-fixes
44498aea293b37af1d463acd9658cdce1ecdf427 drm/i915: also disable south interrupts when handling them
Just in case you want to give it a quick whirl. Since the failed dp aux transaction caused the resume modeset to fail for you (resulting in the black screen) I hope that this should fix both issues.
I'll forward the pull to Dave in a few days since atm I'm stalling a bit for confirmation on another little regression fix. And there's nothing earth-shattering in my -fixes queue right now.
Cheers, Daniel