kernel/git/stable/linux.git/drivers/acpi/ec.c, branch linux-3.14.y

ACPI / EC: Fix race condition in ec_transaction_completed()

2014-07-17T23:21:04+00:00

commit c0d653412fc8450370167a3268b78fc772ff9c87 upstream. There is a race condition in ec_transaction_completed(). When ec_transaction_completed() is called in the GPE handler, it could return true because of (ec->curr == NULL). Then the wake_up() invocation could complete the next command unexpectedly since there is no lock between the 2 invocations. With the previous cleanup, the IBF=0 waiter race need not be handled any more. It's now safe to return a flag from advance_condition() to indicate the requirement of wakeup, the flag is returned from a locked context. The ec_transaction_completed() is now only invoked by the ec_poll() where the ec->curr is ensured to be different from NULL. After cleaning up, the EVT_SCI=1 check should be moved out of the wakeup condition so that an EVT_SCI raised with (ec->curr == NULL) can trigger a QR_SC command. Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931 Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911 Reported-and-tested-by: Gareth Williams Reported-and-tested-by: Hans de Goede Reported-by: Barton Xu Tested-by: Steffen Weber Tested-by: Arthur Chen Signed-off-by: Lv Zheng Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

ACPI / EC: Remove duplicated ec_wait_ibf0() waiter

2014-07-17T23:21:04+00:00

commit 9b80f0f73ae1583c22325ede341c74195847618c upstream. After we've added the first command byte write into advance_transaction(), the IBF=0 waiter is duplicated with the command completion waiter implemented in the ec_poll() because: If IBF=1 blocked the first command byte write invoked in the task context ec_poll(), it would be kicked off upon IBF=0 interrupt or timed out and retried again in the task context. Remove this seperate and duplicate IBF=0 waiter. By doing so we can reduce the overall number of times to access the EC_SC(R) status register. Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931 Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911 Reported-and-tested-by: Gareth Williams Reported-and-tested-by: Hans de Goede Reported-by: Barton Xu Tested-by: Steffen Weber Tested-by: Arthur Chen Signed-off-by: Lv Zheng Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

ACPI / EC: Add asynchronous command byte write support

2014-07-17T23:21:04+00:00

commit f92fca0060fc4dc9227342d0072d75df98c1e5a5 upstream. Move the first command byte write into advance_transaction() so that all EC register accesses that can affect the command processing state machine can happen in this asynchronous state machine advancement function. The advance_transaction() function then can be a complete implementation of an asyncrhonous transaction for a single command so that: 1. The first command byte can be written in the interrupt context; 2. The command completion waiter can also be used to wait the first command byte's timeout; 3. In BURST mode, the follow-up command bytes can be written in the interrupt context directly, so that it doesn't need to return to the task context. Returning to the task context reduces the throughput of the BURST mode and in the worst cases where the system workload is very high, this leads to the hardware driven automatic BURST mode exit. In order not to increase memory consumption, convert 'done' into 'flags' to contain multiple indications: 1. ACPI_EC_COMMAND_COMPLETE: converting from original 'done' condition, indicating the completion of the command transaction. 2. ACPI_EC_COMMAND_POLL: indicating the availability of writing the first command byte. A new command can utilize this flag to compete for the right of accessing the underlying hardware. There is a follow-up bug fix that has utilized this new flag. The 2 flags are important because it also reflects a key concept of IO programs' design used in the system softwares. Normally an IO program running in the kernel should first be implemented in the asynchronous way. And the 2 flags are the most common way to implement its synchronous operations on top of the asynchronous operations: 1. POLL: This flag can be used to block until the asynchronous operations can happen. 2. COMPLETE: This flag can be used to block until the asynchronous operations have completed. By constructing code cleanly in this way, many difficult problems can be solved smoothly. Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931 Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911 Reported-and-tested-by: Gareth Williams Reported-and-tested-by: Hans de Goede Reported-by: Barton Xu Tested-by: Steffen Weber Tested-by: Arthur Chen Signed-off-by: Lv Zheng Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

ACPI / EC: Avoid race condition related to advance_transaction()

2014-07-17T23:21:04+00:00

commit 66b42b78bc1e816f92b662e8888c89195e4199e1 upstream. The advance_transaction() will be invoked from the IRQ context GPE handler and the task context ec_poll(). The handling of this function is locked so that the EC state machine are ensured to be advanced sequentially. But there is a problem. Before invoking advance_transaction(), EC_SC(R) is read. Then for advance_transaction(), there could be race condition around the lock from both contexts. The first one reading the register could fail this race and when it passes the stale register value to the state machine advancement code, the hardware condition is totally different from when the register is read. And the hardware accesses determined from the wrong hardware status can break the EC state machine. And there could be cases that the functionalities of the platform firmware are seriously affected. For example: 1. When 2 EC_DATA(W) writes compete the IBF=0, the 2nd EC_DATA(W) write may be invalid due to IBF=1 after the 1st EC_DATA(W) write. Then the hardware will either refuse to respond a next EC_SC(W) write of the next command or discard the current WR_EC command when it receives a EC_SC(W) write of the next command. 2. When 1 EC_SC(W) write and 1 EC_DATA(W) write compete the IBF=0, the EC_DATA(W) write may be invalid due to IBF=1 after the EC_SC(W) write. The next EC_DATA(R) could never be responded by the hardware. This is the root cause of the reported issue. Fix this issue by moving the EC_SC(R) access into the lock so that we can ensure that the state machine is advanced consistently. Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931 Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911 Reported-and-tested-by: Gareth Williams Reported-and-tested-by: Hans de Goede Reported-by: Barton Xu Tested-by: Steffen Weber Tested-by: Arthur Chen Signed-off-by: Lv Zheng Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

ACPI / EC: Process rather than discard events in acpi_ec_clear

2014-06-07T17:28:12+00:00

commit 3eba563e280101209bad27d40bfc83ddf1489234 upstream. Address a regression caused by commit ad332c8a4533: (ACPI / EC: Clear stale EC events on Samsung systems) After the earlier patch, there was found to be a race condition on some earlier Samsung systems (N150/N210/N220). The function acpi_ec_clear was sometimes discarding a new EC event before its GPE was triggered by the system. In the case of these systems, this meant that the "lid open" event was not registered on resume if that was the cause of the wake, leading to problems when attempting to close the lid to suspend again. After testing on a number of Samsung systems, both those affected by the previous EC bug and those affected by the race condition, it seemed that the best course of action was to process rather than discard the events. On Samsung systems which accumulate stale EC events, there does not seem to be any adverse side-effects of running the associated _Q methods. This patch adds an argument to the static function acpi_ec_sync_query so that it may be used within the acpi_ec_clear loop in place of acpi_ec_query_unlocked which was used previously. With thanks to Stefan Biereigel for reporting the issue, and for all the people who helped test the new patch on affected systems. Fixes: ad332c8a4533 (ACPI / EC: Clear stale EC events on Samsung systems) References: https://lkml.kernel.org/r/532FE3B2.9060808@biereigel-wb.de References: https://bugzilla.kernel.org/show_bug.cgi?id=44161#c173 Reported-by: Stefan Biereigel Signed-off-by: Kieran Clancy Tested-by: Stefan Biereigel Tested-by: Dennis Jansen Tested-by: Nicolas Porcel Tested-by: Maurizio D'Addona Tested-by: Juan Manuel Cabo Tested-by: Giannis Koutsou Tested-by: Kieran Clancy Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

ACPI / EC: Clear stale EC events on Samsung systems

2014-03-06T12:27:23+00:00

A number of Samsung notebooks (530Uxx/535Uxx/540Uxx/550Pxx/900Xxx/etc) continue to log events during sleep (lid open/close, AC plug/unplug, battery level change), which accumulate in the EC until a buffer fills. After the buffer is full (tests suggest it holds 8 events), GPEs stop being triggered for new events. This state persists on wake or even on power cycle, and prevents new events from being registered until the EC is manually polled. This is the root cause of a number of bugs, including AC not being detected properly, lid close not triggering suspend, and low ambient light not triggering the keyboard backlight. The bug also seemed to be responsible for performance issues on at least one user's machine. Juan Manuel Cabo found the cause of bug and the workaround of polling the EC manually on wake. The loop which clears the stale events is based on an earlier patch by Lan Tianyu (see referenced attachment). This patch: - Adds a function acpi_ec_clear() which polls the EC for stale _Q events at most ACPI_EC_CLEAR_MAX (currently 100) times. A warning is logged if this limit is reached. - Adds a flag EC_FLAGS_CLEAR_ON_RESUME which is set to 1 if the DMI system vendor is Samsung. This check could be replaced by several more specific DMI vendor/product pairs, but it's likely that the bug affects more Samsung products than just the five series mentioned above. Further, it should not be harmful to run acpi_ec_clear() on systems without the bug; it will return immediately after finding no data waiting. - Runs acpi_ec_clear() on initialisation (boot), from acpi_ec_add() - Runs acpi_ec_clear() on wake, from acpi_ec_unblock_transactions() References: https://bugzilla.kernel.org/show_bug.cgi?id=44161 References: https://bugzilla.kernel.org/show_bug.cgi?id=45461 References: https://bugzilla.kernel.org/show_bug.cgi?id=57271 References: https://bugzilla.kernel.org/attachment.cgi?id=126801 Suggested-by: Juan Manuel Cabo Signed-off-by: Kieran Clancy Reviewed-by: Lan Tianyu Reviewed-by: Dennis Jansen Tested-by: Kieran Clancy Tested-by: Juan Manuel Cabo Tested-by: Dennis Jansen Tested-by: Maurizio D'Addona Tested-by: San Zamoyski Cc: All applicable Signed-off-by: Rafael J. Wysocki

Merge branches 'acpi-gpe', 'acpi-video', 'acpi-thermal', 'acpi-processor', 'acpi-sleep'

2014-01-12T22:46:55+00:00

* acpi-gpe: ACPI / EC: disable GPE before removing GPE handler ACPI / Button: Fix enabling button GPEs twice * acpi-video: ACPI: Blacklist Win8 OSI for some HP laptop 2013 models ACPI / video: Fix typo in video_detect.c * acpi-thermal: ACPI / thermal: remove const from thermal_zone_device_ops declaration * acpi-processor: ACPI / scan: bail out early if failed to parse APIC ID for CPU * acpi-sleep: ACPI / sleep: remove panic in case hardware has changed after S4

ACPI / EC: Remove unused functions and add prototype declaration in internal.h

2014-01-05T23:13:23+00:00

Adds the prototype declarations of functions acpi_ec_add_query_handler() and acpi_ec_remove_query_handler() in header file internal.h and removes unused functions ec_burst_enable() and ec_burst_disable() in ec.c. This eliminates the following warnings in ec.c: drivers/acpi/ec.c:393:5: warning: no previous prototype for ‘ec_burst_enable’ [-Wmissing-prototypes] drivers/acpi/ec.c:402:5: warning: no previous prototype for ‘ec_burst_disable’ [-Wmissing-prototypes] drivers/acpi/ec.c:531:5: warning: no previous prototype for ‘acpi_ec_add_query_handler’ [-Wmissing-prototypes] drivers/acpi/ec.c:552:6: warning: no previous prototype for ‘acpi_ec_remove_query_handler’ [-Wmissing-prototypes] Signed-off-by: Rashika Kheria Reviewed-by: Josh Triplett Signed-off-by: Rafael J. Wysocki

ACPI / EC: disable GPE before removing GPE handler

2013-12-19T14:56:15+00:00

Adjust the order of disabling the EC GPE and removing its handler to avoid unhandled events. Signed-off-by: Lan Tianyu [rjw: Changelog] Signed-off-by: Rafael J. Wysocki

ACPI: Clean up inclusions of ACPI header files

2013-12-07T00:03:14+00:00

Replace direct inclusions of , and , which are incorrect, with inclusions and remove some inclusions of those files that aren't necessary. First of all, , and should not be included directly from any files that are built for CONFIG_ACPI unset, because that generally leads to build warnings about undefined symbols in !CONFIG_ACPI builds. For CONFIG_ACPI set, includes those files and for CONFIG_ACPI unset it provides stub ACPI symbols to be used in that case. Second, there are ordering dependencies between those files that always have to be met. Namely, it is required that be included prior to so that the acpi_pci_root declarations the latter depends on are always there. And which provides basic ACPICA type declarations should always be included prior to any other ACPI headers in CONFIG_ACPI builds. That also is taken care of including as appropriate. Signed-off-by: Lv Zheng Cc: Greg Kroah-Hartman Cc: Matthew Garrett Cc: Tony Luck Cc: "H. Peter Anvin" Acked-by: Bjorn Helgaas (drivers/pci stuff) Acked-by: Konrad Rzeszutek Wilk (Xen stuff) Signed-off-by: Rafael J. Wysocki