releases/3.16.3/acpi-ec-add-support-to-disallow-qr_ec-to-be-issued-when-sci_evt-isn-t-set.patch

   1 From 3afcf2ece453e1a8c2c6de19cdf06da3772a1b08 Mon Sep 17 00:00:00 2001
   2 From: Lv Zheng <lv.zheng@intel.com>
   3 Date: Thu, 21 Aug 2014 14:41:13 +0800
   4 Subject: ACPI / EC: Add support to disallow QR_EC to be issued when SCI_EVT isn't set
   5
   6 From: Lv Zheng <lv.zheng@intel.com>
   7
   8 commit 3afcf2ece453e1a8c2c6de19cdf06da3772a1b08 upstream.
   9
  10 There is a platform refusing to respond QR_EC when SCI_EVT isn't set
  11 (Acer Aspire V5-573G).
  12
  13 Currently, we rely on the behaviour that the EC firmware can respond
  14 something (for example, 0x00 to indicate "no outstanding events") to
  15 QR_EC even when SCI_EVT is not set, but the reporter has complained
  16 about AC/battery pluging/unpluging and video brightness change delay
  17 on that platform.
  18
  19 This is because the work item that has issued QR_EC has to wait until
  20 timeout in this case, and the _Qxx method evaluation work item queued
  21 after QR_EC one is delayed.
  22
  23 It sounds reasonable to fix this issue by:
  24  1. Implementing SCI_EVT sanity check before issuing QR_EC in the EC
  25     driver's main state machine.
  26  2. Moving QR_EC issuing out of the work queue used by _Qxx evaluation
  27     to a seperate IRQ handling thread.
  28
  29 This patch fixes this issue using solution 1.
  30
  31 By disallowing QR_EC to be issued when SCI_EVT isn't set, we are able to
  32 handle such platform in the EC driver's main state machine. This patch
  33 enhances the state machine in this way to survive with such malfunctioning
  34 EC firmware.
  35
  36 Note that this patch can also fix CLEAR_ON_RESUME quirk which also relies
  37 on the assumption that the platforms are able to respond even when SCI_EVT
  38 isn't set.
  39
  40 Fixes: c0d653412fc8 ACPI / EC: Fix race condition in ec_transaction_completed()
  41 Link: https://bugzilla.kernel.org/show_bug.cgi?id=82611
  42 Reported-and-tested-by: Alexander Mezin <mezin.alexander@gmail.com>
  43 Signed-off-by: Lv Zheng <lv.zheng@intel.com>
  44 Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  45 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  46
  47 ---
  48  drivers/acpi/ec.c |   17 ++++++++++++++++-
  49  1 file changed, 16 insertions(+), 1 deletion(-)
  50
  51 --- a/drivers/acpi/ec.c
  52 +++ b/drivers/acpi/ec.c
  53 @@ -197,6 +197,8 @@ static bool advance_transaction(struct a
  54                                 t->rdata[t->ri++] = acpi_ec_read_data(ec);
  55                                 if (t->rlen == t->ri) {
  56                                         t->flags |= ACPI_EC_COMMAND_COMPLETE;
  57 +                                       if (t->command == ACPI_EC_COMMAND_QUERY)
  58 +                                               pr_debug("hardware QR_EC completion\n");
  59                                         wakeup = true;
  60                                 }
  61                         } else
  62 @@ -208,7 +210,20 @@ static bool advance_transaction(struct a
  63                 }
  64                 return wakeup;
  65         } else {
  66 -               if ((status & ACPI_EC_FLAG_IBF) == 0) {
  67 +               /*
  68 +                * There is firmware refusing to respond QR_EC when SCI_EVT
  69 +                * is not set, for which case, we complete the QR_EC
  70 +                * without issuing it to the firmware.
  71 +                * https://bugzilla.kernel.org/show_bug.cgi?id=86211
  72 +                */
  73 +               if (!(status & ACPI_EC_FLAG_SCI) &&
  74 +                   (t->command == ACPI_EC_COMMAND_QUERY)) {
  75 +                       t->flags |= ACPI_EC_COMMAND_POLL;
  76 +                       t->rdata[t->ri++] = 0x00;
  77 +                       t->flags |= ACPI_EC_COMMAND_COMPLETE;
  78 +                       pr_debug("software QR_EC completion\n");
  79 +                       wakeup = true;
  80 +               } else if ((status & ACPI_EC_FLAG_IBF) == 0) {
  81                         acpi_ec_write_cmd(ec, t->command);
  82                         t->flags |= ACPI_EC_COMMAND_POLL;
  83                 } else