From: Bjorn Helgaas Date: Fri, 19 Aug 2016 08:30:25 +0000 (+0800) Subject: PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db8ff864faf3d281f382a9a294d4e0e3ea0b1266;p=pandora-kernel.git PCI: Work around poweroff & suspend-to-RAM issue on Macbook Pro 11 commit 13cfc732160f7bc7e596128ce34cda361c556966 upstream. Neither soft poweroff (transition to ACPI power state S5) nor suspend-to-RAM (transition to state S3) works on the Macbook Pro 11,4 and 11,5. The problem is related to the [mem 0x7fa00000-0x7fbfffff] space. When we use that space, e.g., by assigning it to the 00:1c.0 Root Port, the ACPI Power Management 1 Control Register (PM1_CNT) at [io 0x1804] doesn't work anymore. Linux does a soft poweroff (transition to S5) by writing to PM1_CNT. The theory about why this doesn't work is: - The write to PM1_CNT causes an SMI - The BIOS SMI handler depends on something in [mem 0x7fa00000-0x7fbfffff] - When Linux assigns [mem 0x7fa00000-0x7fbfffff] to the 00:1c.0 Port, it covers up whatever the SMI handler uses, so the SMI handler no longer works correctly Reserve the [mem 0x7fa00000-0x7fbfffff] space so we don't assign it to anything. This is voodoo programming, since we don't know what the real conflict is, but we've failed to find the root cause. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=103211 Tested-by: thejoe@gmail.com Signed-off-by: Bjorn Helgaas Cc: Rafael J. Wysocki Cc: Lukas Wunner Cc: Chen Yu Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed