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* tty: Only perform flip buffer flush from tty_buffer_flush()Peter Hurley2013-07-241-42/+21
| | | | | | | | | | | | Now that dropping the buffer lock is not necessary (as result of converting the spin lock to a mutex), the flip buffer flush no longer needs to be handled by the buffer work. Simply signal a flush is required; the buffer work will exit the i/o loop, which allows tty_buffer_flush() to proceed. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Ensure single-threaded flip buffer consumer with mutexPeter Hurley2013-07-242-21/+21
| | | | | | | | | | | The buffer work may race with parallel tty_buffer_flush. Use a mutex to guarantee exclusive modify access to the head flip buffer. Remove the unneeded spin lock. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Make driver-side flip buffers locklessPeter Hurley2013-07-241-27/+4
| | | | | | | | | | | Driver-side flip buffer input is already single-threaded; 'publish' the .next link as the last operation on the tail buffer so the 'consumer' sees the already-completed flip buffer. The commit buffer index is already 'published' by driver-side functions. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Track flip buffer memory limit atomicallyPeter Hurley2013-07-242-13/+34
| | | | | | | | | | | | Lockless flip buffers require atomically updating the bytes-in-use watermark. The pty driver also peeks at the watermark value to limit memory consumption to a much lower value than the default; query the watermark with new fn, tty_buffer_space_avail(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Simplify flip buffer list with 0-sized sentinelPeter Hurley2013-07-241-31/+18
| | | | | | | | | | | | | | | Use a 0-sized sentinel to avoid assigning the head ptr from the driver side thread. This also eliminates testing head/tail for NULL. When the sentinel is first 'consumed' by the buffer work (or by tty_buffer_flush()), it is detached from the list but not freed nor added to the free list. Both buffer work and tty_buffer_flush() continue to preserve at least 1 flip buffer to which head & tail is pointed. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Use lockless flip buffer free listPeter Hurley2013-07-241-17/+12
| | | | | | | | | | | | In preparation for lockless flip buffers, make the flip buffer free list lockless. NB: using llist is not the optimal solution, as the driver and buffer work may contend over the llist head unnecessarily. However, test measurements indicate this contention is low. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Use generic names for flip buffer list cursorsPeter Hurley2013-07-241-10/+10
| | | | | Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Merge tty_buffer_find() into tty_buffer_alloc()Peter Hurley2013-07-241-32/+18
| | | | | | | | | tty_buffer_find() implements a simple free list lookaside cache. Merge this functionality into tty_buffer_alloc() to reflect the more traditional alloc/free symmetry. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Factor flip buffer initialization into helper functionPeter Hurley2013-07-241-9/+12
| | | | | | | Factor shared code; prepare for adding 0-sized sentinel flip buffer. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix flip buffer free listPeter Hurley2013-07-241-6/+10
| | | | | | | | | | | Since flip buffers are size-aligned to 256 bytes and all flip buffers 512-bytes or larger are not added to the free list, the free list only contains 256-byte flip buffers. Remove the list search when allocating a new flip buffer. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Compute flip buffer ptrsPeter Hurley2013-07-241-12/+10
| | | | | | | | | | The char_buf_ptr and flag_buf_ptr values are trivially derived from the .data field offset; compute values as needed. Fixes a long-standing type-mismatch with the char and flag ptrs. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Queue buffer work on any available cpuPeter Hurley2013-07-241-1/+1
| | | | | | | | | Scheduling buffer work on the same cpu as the read() thread limits the parallelism now possible between the receive_buf path and the n_tty_read() path. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Special case pty flow controlPeter Hurley2013-07-241-0/+14
| | | | | | | | | | | | | | | The pty driver forces ldisc flow control on, regardless of available receive buffer space, so the writer can be woken whenever unthrottle is called. However, this 'forced throttle' has performance consequences, as multiple atomic operations are necessary to unthrottle and perform the write wakeup for every input line (in canonical mode). Instead, short-circuit the unthrottle if the tty is a pty and perform the write wakeup directly. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Move n_tty_write_wakeup() to avoid forward declarationPeter Hurley2013-07-241-16/+15
| | | | | | | Prepare to special case pty flow control; avoid forward declaration. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Factor throttle/unthrottle into helper functionsPeter Hurley2013-07-241-35/+46
| | | | | | | | Prepare for special handling of pty throttle/unthrottle; factor flow control into helper functions. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Move chars_in_buffer() to factor throttle/unthrottlePeter Hurley2013-07-241-12/+12
| | | | | | | | Prepare to factor throttle and unthrottle into helper functions; relocate chars_in_buffer() to avoid forward declaration. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Only guarantee termios read safety for throttle/unthrottlePeter Hurley2013-07-243-8/+5
| | | | | | | | | | | No tty driver modifies termios during throttle() or unthrottle(). Therefore, only read safety is required. However, tty_throttle_safe and tty_unthrottle_safe must still be mutually exclusive; introduce throttle_mutex for that purpose. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Separate buffer indices to prevent cache-line sharingPeter Hurley2013-07-241-6/+15
| | | | | | | | | | | If the read buffer indices are in the same cache-line, cpus will contended over the cache-line (so called 'false sharing'). Separate the producer-published fields from the consumer-published fields; document the locks relevant to each field. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Don't wait for buffer work in read() loopPeter Hurley2013-07-241-1/+0
| | | | | | | | User-space read() can run concurrently with receiving from device; waiting for receive_buf() to complete is not required. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Fix type mismatches in receive_buf raw copyPeter Hurley2013-07-241-14/+17
| | | | | Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Reset lnext if canonical mode changesPeter Hurley2013-07-241-0/+1
| | | | | | | | | | | | | lnext escapes the next input character as a literal, and must be reset when canonical mode changes (to avoid misinterpreting a special character as a literal if canonical mode is changed back again). lnext is specifically not reset on a buffer flush so as to avoid misinterpreting the next input character as a special character. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Make N_TTY ldisc receive path locklessPeter Hurley2013-07-241-81/+92
| | | | | | | | | | | | | | | | | | | n_tty has a single-producer/single-consumer input model; use lockless publish instead. Use termios_rwsem to exclude both consumer and producer while changing or resetting buffer indices, eg., when flushing. Also, claim exclusive termios_rwsem to safely retrieve the buffer indices from a thread other than consumer or producer (eg., TIOCINQ ioctl). Note the read_tail is published _after_ clearing the newline indicator in read_flags to avoid racing the producer. Drop read_lock spinlock. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Replace canon_data with index comparisonPeter Hurley2013-07-241-16/+6
| | | | | | | | | | | | | | | | canon_data represented the # of lines which had been copied to the receive buffer but not yet copied to the user buffer. The value was tested to determine if input was available in canonical mode (and also to force input overrun if the receive buffer was full but a newline had not been received). However, the actual count was irrelevent; only whether it was non-zero (meaning 'is there any input to transfer?'). This shared count is unnecessary and unsafe with a lockless algorithm. The same check is made by comparing canon_head with read_tail instead. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Access termios values safelyPeter Hurley2013-07-241-5/+39
| | | | | | | | | | | | | Use termios_rwsem to guarantee safe access to the termios values. This is particularly important for N_TTY as changing certain termios settings alters the mode of operation. termios_rwsem must be dropped across throttle/unthrottle since those functions claim the termios_rwsem exclusively (to guarantee safe access to the termios and for mutual exclusion). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Convert termios_mutex to termios_rwsemPeter Hurley2013-07-247-66/+66
| | | | | | | | | termios is commonly accessed unsafely (especially by N_TTY) because the existing mutex forces exclusive access. Convert existing usage. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Remove read_cntPeter Hurley2013-07-241-13/+2
| | | | | | | | | | | Storing the read_cnt creates an unnecessary shared variable between the single-producer (n_tty_receive_buf()) and the single-consumer (n_tty_read()). Compute read_cnt from head & tail instead of storing. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Don't wrap input buffer indices at buffer sizePeter Hurley2013-07-241-51/+60
| | | | | | | | | | Wrap read_buf indices (read_head, read_tail, canon_head) at max representable value, instead of at the N_TTY_BUF_SIZE. This step is necessary to allow lockless reads of these shared variables (by updating the variables atomically). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Get read_cnt through accessorPeter Hurley2013-07-241-18/+23
| | | | | | | Prepare for replacing read_cnt field with computed value. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Deprecate ldisc .chars_in_buffer() methodPeter Hurley2013-07-241-0/+1
| | | | | Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Split n_tty_chars_in_buffer() for reader-only interfacePeter Hurley2013-07-241-3/+8
| | | | | | | | | | N_TTY .chars_in_buffer() method requires serialized access if the current thread is not the single-consumer, n_tty_read(). Separate the internal interface; prepare for lockless read-side. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Line copy to user buffer in canonical modePeter Hurley2013-07-241-33/+77
| | | | | | | | Instead of pushing one char per loop, pre-compute the data length to copy and copy all at once. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* n_tty: Factor canonical mode copy from n_tty_read()Peter Hurley2013-07-241-38/+57
| | | | | | | | Simplify n_tty_read(); extract complex copy algorithm into separate function, canon_copy_to_user(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Make ldisc input flow control concurrency-friendlyPeter Hurley2013-07-243-33/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Although line discipline receiving is single-producer/single-consumer, using tty->receive_room to manage flow control creates unnecessary critical regions requiring additional lock use. Instead, introduce the optional .receive_buf2() ldisc method which returns the # of bytes actually received. Serialization is guaranteed by the caller. In turn, the line discipline should schedule the buffer work item whenever space becomes available; ie., when there is room to receive data and receive_room() previously returned 0 (the buffer work item stops processing if receive_buf2() returns 0). Note the 'no room' state need not be atomic despite concurrent use by two threads because only the buffer work thread can set the state and only the read() thread can clear the state. Add n_tty_receive_buf2() as the receive_buf2() method for N_TTY. Provide a public helper function, tty_ldisc_receive_buf(), to use when directly accessing the receive_buf() methods. Line disciplines not using input flow control can continue to set tty->receive_room to a fixed value and only provide the receive_buf() method. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Simplify tty buffer/ldisc interface with helper functionPeter Hurley2013-07-241-12/+17
| | | | | | | | | | | | | | | | | | | | | | Ldisc interface functions must be called with interrupts enabled. Separating the ldisc calls into a helper function simplies the eventual removal of the spinlock. Note that access to the buf->head ptr outside the spinlock is safe here because; * __tty_buffer_flush() is prevented from running while buffer work performs i/o, * tty_buffer_find() only assigns buf->head if the flip buffer list is empty (which is never the case in flush_to_ldisc() since at least one buffer is always left in the list after use) Access to the read index outside the spinlock is safe here for the same reasons. Update the buffer's read index _after_ the data has been received by the ldisc. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Don't change receive_room for ioctl(TIOCSETD)Peter Hurley2013-07-241-3/+0
| | | | | | | | | tty_set_ldisc() is guaranteed exclusive use of the line discipline by tty_ldisc_lock_pair_timeout(); shutting off input by resetting receive_room is unnecessary. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Clarify multiple-references comment in TIOCSETD ioctlPeter Hurley2013-07-241-4/+6
| | | | | Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix hangup race with TIOCSETD ioctlPeter Hurley2013-07-241-4/+2
| | | | | | | The hangup may already have happened; check for that state also. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Clarify ldisc variablePeter Hurley2013-07-241-7/+7
| | | | | | | | Rename o_ldisc to avoid confusion with the ldisc of the 'other' tty. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Replace ldisc locking with ldisc_semPeter Hurley2013-07-243-288/+50
| | | | | | | | | | | | | | | | | | | | | | Line discipline locking was performed with a combination of a mutex, a status bit, a count, and a waitqueue -- basically, a rw semaphore. Replace the existing combination with an ld_semaphore. Fixes: 1) the 'reference acquire after ldisc locked' bug 2) the over-complicated halt mechanism 3) lock order wrt. tty_lock() 4) dropping locks while changing ldisc 5) previously unidentified deadlock while locking ldisc from both linked ttys concurrently 6) previously unidentified recursive deadlocks Adds much-needed lockdep diagnostics. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Add lock/unlock ldisc pair functionsPeter Hurley2013-07-241-0/+87
| | | | | | | | | Just as the tty pair must be locked in a stable sequence (ie, independent of which is consider the 'other' tty), so must the ldisc pair be locked in a stable sequence as well. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix tty_ldisc_lock name collisionPeter Hurley2013-07-242-25/+25
| | | | | | | | The file scope spinlock identifier, tty_ldisc_lock, will collide with the file scope lock function tty_ldisc_lock() so rename it. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'acpi-video-3.11' of ↵Linus Torvalds2013-07-215-27/+110
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull ACPI video support fixes from Rafael Wysocki: "I'm sending a separate pull request for this as it may be somewhat controversial. The breakage addressed here is not really new and the fixes may not satisfy all users of the affected systems, but we've had so much back and forth dance in this area over the last several weeks that I think it's time to actually make some progress. The source of the problem is that about a year ago we started to tell BIOSes that we're compatible with Windows 8, which we really need to do, because some systems shipping with Windows 8 are tested with it and nothing else, so if we tell their BIOSes that we aren't compatible with Windows 8, we expose our users to untested BIOS/AML code paths. However, as it turns out, some Windows 8-specific AML code paths are not tested either, because Windows 8 actually doesn't use the ACPI methods containing them, so if we declare Windows 8 compatibility and attempt to use those ACPI methods, things break. That occurs mostly in the backlight support area where in particular the _BCM and _BQC methods are plain unusable on some systems if the OS declares Windows 8 compatibility. [ The additional twist is that they actually become usable if the OS says it is not compatible with Windows 8, but that may cause problems to show up elsewhere ] Investigation carried out by Matthew Garrett indicates that what Windows 8 does about backlight is to leave backlight control up to individual graphics drivers. At least there's evidence that it does that if the Intel graphics driver is used, so we've decided to follow Windows 8 in that respect and allow i915 to control backlight (Daniel likes that part). The first commit from Aaron Lu makes ACPICA export the variable from which we can infer whether or not the BIOS believes that we are compatible with Windows 8. The second commit from Matthew Garrett prepares the ACPI video driver by making it initialize the ACPI backlight even if it is not going to be used afterward (that is needed for backlight control to work on Thinkpads). The third commit implements the actual workaround making i915 take over backlight control if the firmware thinks it's dealing with Windows 8 and is based on the work of multiple developers, including Matthew Garrett, Chun-Yi Lee, Seth Forshee, and Aaron Lu. The final commit from Aaron Lu makes us follow Windows 8 by informing the firmware through the _DOS method that it should not carry out automatic brightness changes, so that brightness can be controlled by GUI. Hopefully, this approach will allow us to avoid using blacklists of systems that should not declare Windows 8 compatibility just to avoid backlight control problems in the future. - Change from Aaron Lu makes ACPICA export a variable which can be used by driver code to determine whether or not the BIOS believes that we are compatible with Windows 8. - Change from Matthew Garrett makes the ACPI video driver initialize the ACPI backlight even if it is not going to be used afterward (that is needed for backlight control to work on Thinkpads). - Fix from Rafael J Wysocki implements Windows 8 backlight support workaround making i915 take over bakclight control if the firmware thinks it's dealing with Windows 8. Based on the work of multiple developers including Matthew Garrett, Chun-Yi Lee, Seth Forshee, and Aaron Lu. - Fix from Aaron Lu makes the kernel follow Windows 8 by informing the firmware through the _DOS method that it should not carry out automatic brightness changes, so that brightness can be controlled by GUI" * tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI / video: no automatic brightness changes by win8-compatible firmware ACPI / video / i915: No ACPI backlight if firmware expects Windows 8 ACPI / video: Always call acpi_video_init_brightness() on init ACPICA: expose OSI version
| * ACPI / video: no automatic brightness changes by win8-compatible firmwareAaron Lu2013-07-181-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Starting from win8, MS backlight control driver will set bit 2 of the parameter of control method _DOS, to inform firmware it should not perform any automatic brightness changes. This mostly affects hotkey notification deliver - if we do not set this bit, on hotkey press, firmware may choose to adjust brightness level instead of sending out notification and doing nothing. So this patch sets bit 2 when calling _DOS so that GUIs can show the notification window on hotkey press. This behavior change is only necessary for win8 systems. The MS document on win8 backlight control is here: http://msdn.microsoft.com/en-US/library/windows/hardware/jj159305 References: https://bugzilla.kernel.org/show_bug.cgi?id=52951 References: https://bugzilla.kernel.org/show_bug.cgi?id=56711 Reported-by: Micael Dias <kam1kaz3@gmail.com> Reported-by: Dan Garton <dan.garton@gmail.com> Reported-by: Bob Ziuchkovski <bob.ziuchkovski@gmail.com> Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| * ACPI / video / i915: No ACPI backlight if firmware expects Windows 8Rafael J. Wysocki2013-07-184-9/+94
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | According to Matthew Garrett, "Windows 8 leaves backlight control up to individual graphics drivers rather than making ACPI calls itself. There's plenty of evidence to suggest that the Intel driver for Windows [8] doesn't use the ACPI interface, including the fact that it's broken on a bunch of machines when the OS claims to support Windows 8. The simplest thing to do appears to be to disable the ACPI backlight interface on these systems". There's a problem with that approach, however, because simply avoiding to register the ACPI backlight interface if the firmware calls _OSI for Windows 8 may not work in the following situations: (1) The ACPI backlight interface actually works on the given system and the i915 driver is not loaded (e.g. another graphics driver is used). (2) The ACPI backlight interface doesn't work on the given system, but there is a vendor platform driver that will register its own, equally broken, backlight interface if not prevented from doing so by the ACPI subsystem. Therefore we need to allow the ACPI backlight interface to be registered until the i915 driver is loaded which then will unregister it if the firmware has called _OSI for Windows 8 (or will register the ACPI video driver without backlight support if not already present). For this reason, introduce an alternative function for registering ACPI video, acpi_video_register_with_quirks(), that will check whether or not the ACPI video driver has already been registered and whether or not the backlight Windows 8 quirk has to be applied. If the quirk has to be applied, it will block the ACPI backlight support and either unregister the backlight interface if the ACPI video driver has already been registered, or register the ACPI video driver without the backlight interface otherwise. Make the i915 driver use acpi_video_register_with_quirks() instead of acpi_video_register() in i915_driver_load(). This change is based on earlier patches from Matthew Garrett, Chun-Yi Lee and Seth Forshee and includes a fix from Aaron Lu's. References: https://bugzilla.kernel.org/show_bug.cgi?id=51231 Tested-by: Aaron Lu <aaron.lu@intel.com> Tested-by: Igor Gnatenko <i.gnatenko.brain@gmail.com> Tested-by: Yves-Alexis Perez <corsac@debian.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Aaron Lu <aaron.lu@intel.com> Acked-by: Matthew Garrett <matthew.garrett@nebula.com>
| * ACPI / video: Always call acpi_video_init_brightness() on initMatthew Garrett2013-07-181-3/+8
| | | | | | | | | | | | | | | | | | | | | | | | We have to call acpi_video_init_brightness() even if we're not going to initialise the backlight - Thinkpads seem to use this as the trigger for enabling ACPI notifications rather than handling it in firmware. [rjw: Drop the brightness object created by acpi_video_init_brightness() if we are not going to use it.] Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| * ACPICA: expose OSI versionAaron Lu2013-07-181-13/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Expose acpi_gbl_osi_data so that code outside of ACPICA can check the value of the last successfull _OSI call. The definitions for OSI versions are moved to actypes.h so that other components can access them too. Based on a patch from Matthew Garrett which in turn was based on an earlier patch from Seth Forshee. [rjw: Changelog] Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* | Merge tag 'staging-3.11-rc2' of ↵Linus Torvalds2013-07-21154-91615/+20
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging Pull staging tree fixes from Greg KH: "Here are a few iio driver fixes for 3.11-rc2. They are still spread across drivers/iio and drivers/staging/iio so they are coming in through this tree. I've also removed the drivers/staging/csr/ driver as the developers who originally sent it to me have moved on to other companies, and CSR still will not send us the specs for the device, making the driver pretty much obsolete and impossible to fix up. Deleting it now prevents people from sending in lots of tiny codingsyle fixes that will never go anywhere. It also helps to offset the large lustre filesystem merge that happened in 3.11-rc1 in the overall 3.11.0 diffstat. :)" * tag 'staging-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: staging: csr: remove driver iio: lps331ap: Fix wrong in_pressure_scale output value iio staging: fix lis3l02dq, read error handling staging:iio:ad7291: add missing .driver_module to struct iio_info iio: ti_am335x_adc: add missing .driver_module to struct iio_info iio: mxs-lradc: Remove useless check in read_raw iio: mxs-lradc: Fix misuse of iio->trig iio: inkern: fix iio_convert_raw_to_processed_unlocked iio: Fix iio_channel_has_info iio:trigger: device_unregister->device_del to avoid double free iio: dac: ad7303: fix error return code in ad7303_probe()
| * \ Merge tag 'iio-fixes-for-3.11a' of ↵Greg Kroah-Hartman2013-07-178-16/+20
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus Jonathan writes: The first round of IIO fixes for the 3.11 cycle. This set is larger than I would like, partly due to my lack of review time in the weeks before the merge window and partly because a couple of large drivers and the subsystem as a whole seem to be getting a lot more exposure and testing recently. 1) A long term bug in trigger handling gave a double free of the device. 2) Wrong return value handling means offsets are ignored in iio_convert_raw_to_processed_unlocked. 3) The iio_channel_has_info utility function was incorrectly updated during the recent info_mask split, this is now fixed. 4) mxs-lradc has a couple of little fixes. 5) A couple of missing .driver_module entries meant that drivers could be removed from underneath their users. 6) Error path fixes for ad7303 and lis3l02dq. 7) The scale value for presure in the lps331ap driver was out by a factor of 100.
| | * | iio: lps331ap: Fix wrong in_pressure_scale output valueJacek Anaszewski2013-07-161-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes improper in_pressure_scale output that is returned by the lps331ap barometer sensor driver. According to the documentation the pressure after applying the scale has to be expressed in kilopascal units. With erroneous implementation the scale value larger by two orders of magnitude is returned - 2441410 instead of 24414. Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Denis Ciocca <denis.ciocca@st.com> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
| | * | iio staging: fix lis3l02dq, read error handlingPeter Meerwald2013-07-091-0/+2
| | | | | | | | | | | | | | | | | | | | Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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