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authorLv Zheng <lv.zheng@intel.com>2015-01-14 19:28:47 +0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-01-23 22:06:49 +0100
commit74443bbed72ab22ee005ecb6ecdc657a8018e1db (patch)
treef982a768793dc655eba51929a95ac4c11aaed338 /ipc/msgutil.c
parentf3e14329517ee190d34455d729430ef9d0473675 (diff)
ACPI / EC: Fix issues related to the SCI_EVT handling
This patch fixes 2 issues related to the draining behavior. But it doesn't implement the draining support, it only cleans up code so that further draining support is possible. The draining behavior is expected by some platforms (for example, Samsung) where SCI_EVT is set only once for a set of events and might be cleared for the very first QR_EC command issued after SCI_EVT is set. EC firmware on such platforms will return 0x00 to indicate "no outstanding event". Thus after seeing an SCI_EVT indication, EC driver need to fetch events until 0x00 returned (see acpi_ec_clear()). Issue 1 - acpi_ec_submit_query(): It's reported on Samsung laptops that SCI_EVT isn't checked when the transactions are advanced in ec_poll(), which leads to SCI_EVT triggering source lost: If no EC GPE IRQs are arrived after that, EC driver cannot detect this event and handle it. See comment 244/247 for kernel bugzilla 44161. This patch fixes this issue by moving SCI_EVT checks into advance_transaction(). So that SCI_EVT is checked each time we are going to handle the EC firmware indications. And this check will happen for both IRQ context and task context. Since after doing that, SCI_EVT is also checked after completing a transaction, ec_check_sci() and ec_check_sci_sync() can be removed. Issue 2 - acpi_ec_complete_query(): We expect to clear EC_FLAGS_QUERY_PENDING to allow queuing another draining QR_EC after writing a QR_EC command and before reading the event. After reading the event, SCI_EVT might be cleared by the firmware, thus it may not be possible to queue such a draining QR_EC at that time. But putting the EC_FLAGS_QUERY_PENDING clearing code after start_transaction() is wrong as there are chances that after start_transaction(), QR_EC can fail to be sent. If this happens, EC_FLAG_QUERY_PENDING will be cleared earlier. As a consequence, the draining QR_EC will also be queued earlier than expected. This patch also moves this code into advance_transaction() where QR_EC is just sent (ACPI_EC_COMMAND_POLL flagged) to fix this issue. Notes: 1. After introducing the 2 SCI_EVT related handlings into advance_transaction(), a next QR_EC can be queued right after writing the current QR_EC command and before reading the event. But this still hasn't implemented the draining behavior as the draining support requires: If a previous returned event value isn't 0x00, a draining QR_EC need to be issued even when SCI_EVT isn't set. 2. In this patch, acpi_os_execute() is also converted into a seperate work item to avoid invoking kmalloc() in the atomic context. We can do this because of the previous global lock fix. 3. Originally, EC_FLAGS_EVENT_PENDING is also used to avoid queuing up multiple work items (created by acpi_os_execute()), this can be covered by only using a single work item. But this patch still keeps this flag as there are different usages in the driver initialization steps relying on this flag. Link: https://bugzilla.kernel.org/show_bug.cgi?id=44161 Reported-by: Kieran Clancy <clancy.kieran@gmail.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'ipc/msgutil.c')
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