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authornjl <njl@FreeBSD.org>2005-10-25 21:15:47 +0000
committernjl <njl@FreeBSD.org>2005-10-25 21:15:47 +0000
commitbcff7c3a7de41025505a4d318fe5754606ef949b (patch)
tree8b60277dbccc3e5d2198d53a64fe7e38865f3222 /sys/dev/uart/uart_bus_pci.c
parentb61364c6ec8683f89e223ec94bc4eccb41a023be (diff)
downloadFreeBSD-src-bcff7c3a7de41025505a4d318fe5754606ef949b.zip
FreeBSD-src-bcff7c3a7de41025505a4d318fe5754606ef949b.tar.gz
If we're trying to use C2/3 and reads from the register are returning
immediately, back off to the next higher Cx sleep state. Some machines with a Via chipset report a valid C3 but a register read doesn't actually halt the CPU. This would cause the machine to appear unresponsive as it repeatedly called cpu_idle() which immediately returned. Causing interrupts (i.e. by pressing the power button) would cause the system to make forward progress, showing that it wasn't actually hung. Also, enable interrupts a little earlier. We don't need them disabled to calculate the delta time for the read. Reported by: silby MFC after: 2 weeks
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