The only additional information I have is that the irq occurs on a regular 6.47s interval.
Can anyone comment on the mechanism? bryan. On Tue, Dec 7, 2010 at 5:08 PM, Bryan Freed <bfr...@chromium.org> wrote: > I have a pineview system with VGA output that takes anywhere from 1 to 5 > seconds to detect an external monitor plug in/out, and I am trying to reduce > that latency. But I do not know how hotplug detection works. > > My first sign of detection is in i915_driver_irq_handler() where we > read PORT_HOTPLUG_STAT (0x61114). We quickly get > to i915_hotplug_work_func() and drm_sysfs_hotplug_event() after that, but > just getting to i915_driver_irq_handler() takes 1 to 5 seconds. > > My questions are 1) what takes so long to trigger the irq, and 2) what is > the irq mechanism? > > I first thought the i915 was polling over ddc to detect a monitor status > change. But I do not see any activity when I probe DDC_DATA or DDC_CLK. > I have not probed while plugging in an actual monitor since that removes my > easy-to-probe point. > > Does i915 look for a glitch on one of the signals before it probes DDC? > > bryan. > > >
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