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    ACPI / EC: Add support to disallow QR_EC to be issued when SCI_EVT isn't set · 3afcf2ec
    Lv Zheng 提交于
    There is a platform refusing to respond QR_EC when SCI_EVT isn't set
    (Acer Aspire V5-573G).
    
    Currently, we rely on the behaviour that the EC firmware can respond
    something (for example, 0x00 to indicate "no outstanding events") to
    QR_EC even when SCI_EVT is not set, but the reporter has complained
    about AC/battery pluging/unpluging and video brightness change delay
    on that platform.
    
    This is because the work item that has issued QR_EC has to wait until
    timeout in this case, and the _Qxx method evaluation work item queued
    after QR_EC one is delayed.
    
    It sounds reasonable to fix this issue by:
     1. Implementing SCI_EVT sanity check before issuing QR_EC in the EC
        driver's main state machine.
     2. Moving QR_EC issuing out of the work queue used by _Qxx evaluation
        to a seperate IRQ handling thread.
    
    This patch fixes this issue using solution 1.
    
    By disallowing QR_EC to be issued when SCI_EVT isn't set, we are able to
    handle such platform in the EC driver's main state machine. This patch
    enhances the state machine in this way to survive with such malfunctioning
    EC firmware.
    
    Note that this patch can also fix CLEAR_ON_RESUME quirk which also relies
    on the assumption that the platforms are able to respond even when SCI_EVT
    isn't set.
    
    Fixes: c0d65341 ACPI / EC: Fix race condition in ec_transaction_completed()
    Link: https://bugzilla.kernel.org/show_bug.cgi?id=82611Reported-and-tested-by: NAlexander Mezin <mezin.alexander@gmail.com>
    Signed-off-by: NLv Zheng <lv.zheng@intel.com>
    Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
    Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
    3afcf2ec
ec.c 30.4 KB