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  1. 07 Jul, 2014 2 commits
    • Lv Zheng's avatar
      ACPI / EC: Add asynchronous command byte write support · f92fca00
      Lv Zheng authored 
      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=59911Reported-and-tested-by: default avatarGareth Williams <gareth@garethwilliams.me.uk>
Reported-and-tested-by: default avatarHans de Goede <jwrdegoede@fedoraproject.org>
Reported-by: default avatarBarton Xu <tank.xuhan@gmail.com>
Tested-by: default avatarSteffen Weber <steffen.weber@gmail.com>
Tested-by: default avatarArthur Chen <axchen@nvidia.com>
Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      f92fca00
    • Lv Zheng's avatar
      ACPI / EC: Avoid race condition related to advance_transaction() · 66b42b78
      Lv Zheng authored 
      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=59911Reported-and-tested-by: default avatarGareth Williams <gareth@garethwilliams.me.uk>
Reported-and-tested-by: default avatarHans de Goede <jwrdegoede@fedoraproject.org>
Reported-by: default avatarBarton Xu <tank.xuhan@gmail.com>
Tested-by: default avatarSteffen Weber <steffen.weber@gmail.com>
Tested-by: default avatarArthur Chen <axchen@nvidia.com>
Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      66b42b78
  3. 06 Jul, 2014 4 commits
    • Linus Torvalds's avatar
      Linux 3.16-rc4 · cd3de83f
      Linus Torvalds authored
      cd3de83f
    • Linus Torvalds's avatar
      Merge tag 'dt-for-linus' of git://git.secretlab.ca/git/linux · 100193f5
      Linus Torvalds authored 
      Pull devicetree bugfix from Grant Likely:
 "Important bug fix for parsing 64-bit addresses on 32-bit platforms.
  Without this patch the kernel will try to use memory ranges that
  cannot be reached"

* tag 'dt-for-linus' of git://git.secretlab.ca/git/linux:
  of: Check for phys_addr_t overflows in early_init_dt_add_memory_arch
      100193f5
    • Linus Torvalds's avatar
      Merge tag 'scsi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 8addf0c7
      Linus Torvalds authored 
      Pull SCSI fixes from James Bottomley:
 "This is a set of 13 fixes, a MAINTAINERS update and a sparse update.
  The fixes are mostly correct value initialisations, avoiding NULL
  derefs and some uninitialised pointer avoidance.

  All the patches have been incubated in -next for a few days.  The
  final patch (use the scsi data buffer length to extract transfer size)
  has been rebased to add a cc to stable, but only the commit message
  has changed"

* tag 'scsi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  [SCSI] use the scsi data buffer length to extract transfer size
  virtio-scsi: fix various bad behavior on aborted requests
  virtio-scsi: avoid cancelling uninitialized work items
  ibmvscsi: Add memory barriers for send / receive
  ibmvscsi: Abort init sequence during error recovery
  qla2xxx: Fix sparse warning in qla_target.c.
  bnx2fc: Improve stats update mechanism
  bnx2fc: do not scan uninitialized lists in case of error.
  fc: ensure scan_work isn't active when freeing fc_rport
  pm8001: Fix potential null pointer dereference and memory leak.
  MAINTAINERS: Update LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI) maintainers Email IDs
  be2iscsi: remove potential junk pointer free
  be2iscsi: add an missing goto in error path
  scsi_error: set DID_TIME_OUT correctly
  scsi_error: fix invalid setting of host byte
      8addf0c7
    • Linus Torvalds's avatar
      Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux · 110e4308
      Linus Torvalds authored 
      Pull drm fixes from Dave Airlie:
 "i915, tda998x and vmwgfx fixes,

  The main one is i915 fix for missing VGA connectors, along with some
  fixes for the tda998x from Russell fixing some modesetting problems.

  (still on holidays, but got a spare moment to find these)"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/vmwgfx: Fix incorrect write to read-only register v2:
  drm/i915: Drop early VLV WA to fix Voltage not getting dropped to Vmin
  drm/i915: only apply crt_present check on VLV
  drm/i915: Wait for vblank after enabling the primary plane on BDW
  drm/i2c: tda998x: add some basic mode validation
  drm/i2c: tda998x: faster polling for edid
  drm/i2c: tda998x: move drm_i2c_encoder_destroy call
      110e4308
  5. 05 Jul, 2014 12 commits
  7. 04 Jul, 2014 15 commits
  9. 03 Jul, 2014 7 commits
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