ACPI: DMI init_set_sci_en_on_resume for multiple Lenovo ThinkPads
Multiple Lenovo ThinkPad models with Intel Core i5/i7 CPUs can successfully suspend/resume once, and then hang on the second s/r cycle. We got confirmation that this was due to a BIOS defect. The BIOS did not properly set SCI_EN coming out of S3. The BIOS guys hinted that The Other Leading OS ignores the fact that hardware owns the bit and sets it manually. In any case, an existing DMI table exists for machines where this defect is a known problem. Lenovo promise to fix their BIOS, but for folks who either won't or can't upgrade their BIOS, allow Linux to workaround the issue. https://bugzilla.kernel.org/show_bug.cgi?id=15407 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/532374 Confirmed by numerous testers in the launchpad bug that using acpi_sleep=sci_force_enable fixes the issue. We add the machines to acpisleep_dmi_table[] to automatically enable this workaround. Cc: stable@kernel.org Cc: Colin King <colin.king@canonical.com> Signed-off-by: Alex Chiang <achiang@canonical.com> Signed-off-by: Len Brown <len.brown@intel.com>
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