releases/4.9.170/acpi-sbs-fix-gpe-storm-on-recent-macbookpro-s.patch

   1 From f34983a7c3ef9a4591986163d084eb7a4c7218f2 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Ronald=20Tschal=C3=A4r?= <ronald@innovation.ch>
   3 Date: Sun, 30 Sep 2018 19:52:51 -0700
   4 Subject: ACPI / SBS: Fix GPE storm on recent MacBookPro's
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   8
   9 [ Upstream commit ca1721c5bee77105829cbd7baab8ee0eab85b06d ]
  10
  11 On Apple machines, plugging-in or unplugging the power triggers a GPE
  12 for the EC. Since these machines expose an SBS device, this GPE ends
  13 up triggering the acpi_sbs_callback(). This in turn tries to get the
  14 status of the SBS charger. However, on MBP13,* and MBP14,* machines,
  15 performing the smbus-read operation to get the charger's status triggers
  16 the EC's GPE again. The result is an endless re-triggering and handling
  17 of that GPE, consuming significant CPU resources (> 50% in irq).
  18
  19 In the end this is quite similar to commit 3031cddea633 (ACPI / SBS:
  20 Don't assume the existence of an SBS charger), except that on the above
  21 machines a status of all 1's is returned. And like there, we just want
  22 ignore the charger here.
  23
  24 Link: https://bugzilla.kernel.org/show_bug.cgi?id=198169
  25 Signed-off-by: Ronald TschalÃ¤r <ronald@innovation.ch>
  26 Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  27 Signed-off-by: Sasha Levin <sashal@kernel.org>
  28 ---
  29  drivers/acpi/sbs.c | 8 ++++++--
  30  1 file changed, 6 insertions(+), 2 deletions(-)
  31
  32 diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
  33 index ad0b13ad4bbb..4a76000bcf7a 100644
  34 --- a/drivers/acpi/sbs.c
  35 +++ b/drivers/acpi/sbs.c
  36 @@ -443,9 +443,13 @@ static int acpi_ac_get_present(struct acpi_sbs *sbs)
  37
  38         /*
  39          * The spec requires that bit 4 always be 1. If it's not set, assume
  40 -        * that the implementation doesn't support an SBS charger
  41 +        * that the implementation doesn't support an SBS charger.
  42 +        *
  43 +        * And on some MacBooks a status of 0xffff is always returned, no
  44 +        * matter whether the charger is plugged in or not, which is also
  45 +        * wrong, so ignore the SBS charger for those too.
  46          */
  47 -       if (!((status >> 4) & 0x1))
  48 +       if (!((status >> 4) & 0x1) || status == 0xffff)
  49                 return -ENODEV;
  50
  51         sbs->charger_present = (status >> 15) & 0x1;
  52 --
  53 2.19.1
  54