If there's no power sequencer assigned to the port currently we can't
very well have vdd or panel power enabled either. If we would try to
check that from the pps registers we'd need to pick a power seqeuncer
and kick it. So let's skip the register read and the kick.

Note that there's still a bit an issue about correctly recovering pps
state from resume if the bios is nasty: With this check we'll always
assume that the pps is off. But that's better done in a follow-up
patch and it shouldn't be too harmful - at most we waste time enabling
the pps if it's on already.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
[danvet: Add note about resume issues Imre spotted.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

When we pick a new power sequencer for the port but we're not doing a
full modeset, the power sequencer may have locked on to another port (or
no port). So kick it a bit to make sure it controls the port we want.

Again just like when we attempt to actually enable the DP port, we
must first write the port register with the approriate value except
the enable bit, and then we must enable the port to make the power
sequencer happy. In this case since we don't want the port actually
enabled we just toggle it on and immediately back off. Going forward
the power sequencer will keep working on that specific port until again
moved to another port.

v2: Refine the kick procedure
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

When switching from one pipe to another, the power sequencer of the new
pipe seems to need a bit of kicking to lock into the port. Even the vdd
force bit doesn't work before the power sequencer has been sufficiently
kicked, so this must be done before any AUX transactions are attempted.

After extensive experimentation I've determined that it's sufficient
to first write the port register with the correct values except the
port must remain disabled, then we can do a second write to enable the
port, after which the power sequencer is operational and allows the port
to start up properly.

Contrary to my earlier theories we don't need to enable the port with
the idle pattern, so let's just use training pattern 1 as that's what
other platforms use here.

v2: Refine the kick procedure
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

There's no point in checking if the data lanes came out of reset after
link training. If the data lanes aren't ready link training will fail
anyway.
Suggested-by: Todd Previte <tprevite@gmail.com>
Cc: Todd Previte <tprevite@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Acked-by: Todd Previte <tprevite@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Just grab the pps_mutex once and do all the pps panel startup operations
while holding the mutex instead of grabbing the mutex separately for
each individual step.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

We'll be needing to the call the power seqeuencer functions while
already holding pps_mutex, so split the locking out to small wrapper
functions.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Since we read the current power seqeuncer delays from the registers
(as well as looking at the vbt and spec values) we may end up
corrupting delays we already initialized when we switch to another
pipe and the power seqeuncer there has different values currently
in the registers.

So make sure we only initialize the delays once even if
intel_dp_init_panel_power_sequencer() gets called multiple times.

There was some discussion in the review about when exactly we need to
unlock the pps. Quoting Bspec:

"If this bit is not a zero, it activates the register write protect
 and writes to those registers will be ignored unless the write
 protect key value is set in the panel sequencing control register."
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
[danvet: Add Bspec quote per review discussion between Imre and
Ville.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The power seqeuncer delays are fixed for a given panel, so we can keep
them around once computed.

Not that on VLV/CHV we still re-compute them every time we initialize
the power seqeuncer registers, but that will change soon enough.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

want_panel_vdd is a bool so it can't cope with interleaving on/off calls
from multiple threads. If we want to make that possible we'd need to
convert want_panel_vdd into a proper ref count. But an easier fix is to
remove the high level vdd on/off calls from detect/hpd code paths and
just rely on the delayed vdd off to avoid needless vdd on<->off ping
pong.

After this change only the encoder enable/disable paths use the high
level functions, which is fine since both the on and off low level edp
vdd calls from intel_dp_aux_ch() happen without dropping pps_mutex in
between and so want_panel_vdd can't change in between.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Only ports B and C have the power sequencer and backlight controls,
so complain if we ever try to register an eDP connector on some other
port.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Because I got annoyed that I had to document what values "int
ddi_personality" is supposed to hold.

A good side-effect of this change is that now the compilers can do
some additional checks on our code, which may prevent some bugs in the
future. A bad side-effect of this change is that now the compilers do
some additional checks on our code and complain when a switch
statement doesn't check for all possible values, so we need to add
"default" cases to all those switches. Hopefully, this may help
preventing confusions against DRM_MODE_CONNECTOR_* and
DRM_MODE_ENCODER_*.

I guess that just by looking at the patch, some people will think this
change is not worth its benefits. In this case, I don't really mind
dropping the patch.

Also, there's probably still a few more places where we can
s/int/enum intel_output_type/, but we can change that later, when we
spot the places.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Resolve conflict due to reordered patches.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This will simplify things later on. No functional changes.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Everything else can be derived from that. No functional changes.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Most importantly, "i" need not be the universal variable used for
everything. No functional changes.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Const is good.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

In preparation for some additional cleanup. No functional changes.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The fb check introduced to drm_plane_helper_check_update() just make this
check impossible to branch in.
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

We can't let visible set true while the fb is null, some places of
the code only check for visible to base its decisions.
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

use_mmio_flip() makes sure we only enable MMIO flips on gen5+. So we
don't need to take into account older devices.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

There is no point in flipping a buffer for a disabled crtc.
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This patch includes the Gen9 batch buffer to generate
a 'golden context' for that product family.
Signed-off-by: Armin Reese <armin.c.reese@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The file drivers/gpu/drm/i915/intel_renderstate_gen8.c is
updated to the version created by IGT null_state_gen
Signed-off-by: Armin Reese <armin.c.reese@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

libva uses chained batch buffers in a way that the command parser
can't generally handle. Fortunately, libva doesn't need to write
registers from batch buffers in the way that mesa does, so this
patch causes the driver to fall back to non-secure dispatch if
the parser detects a chained batch buffer.

Note: The 2nd hunk to munge the error code of the parser looks a bit
superflous. At least until we have the batch copy code ready and can
run the cmd parser in granting mode. But it isn't since we still need
to let existing libva buffers pass (though not with elevated privs
ofc!).

Testcase: igt/gem_exec_parse/chained-batch
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
[danvet: Add note - this confused me in review and Brad clarified
things (after a few mails ...).]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

This allows the cursor plane to be updated the same way as primary and sprites,
and same set_property handler is used for all of these planes.

v2 (by Matt Roper): Rework to apply to latest di-nightly codebase.  The
        switch to split check/commit plane programming changed the code
        flow enough that the original patch could no longer be applied.
Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Tested-by (IVB): Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

If these flags are on the object level it will be more difficult to allow
for multiple VMAs per object.

v2: Simplification and cleanup after code review comments (Chris Wilson).
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

- suspend/resume/freeze/thaw unification from Imre
- wa list improvements from Mika&Arun
- display pll precomputation from Ander Conselvan, this removed the last
  ->mode_set callbacks, a big step towards implementing atomic modesets
- more kerneldoc for the interrupt code
- 180 rotation for cursors (Ville&Sonika)
- ULT/ULX feature check macros cleaned up thanks to Damien
- piles and piles of fixes all over, bug team seems to work!

* tag 'drm-intel-next-2014-10-24' of git://anongit.freedesktop.org/drm-intel: (61 commits)
  drm/i915: Update DRIVER_DATE to 20141024
  drm/i915: add comments on what stage a given PM handler is called
  drm/i915: unify switcheroo and legacy suspend/resume handlers
  drm/i915: add poweroff_late handler
  drm/i915: sanitize suspend/resume helper function names
  drm/i915: unify S3 and S4 suspend/resume handlers
  drm/i915: disable/re-enable PCI device around S4 freeze/thaw
  drm/i915: enable output polling during S4 thaw
  drm/i915: check for GT faults in all resume handlers and driver load time
  drm/i915: remove unused restore_gtt_mappings optimization during suspend
  drm/i915: fix S4 suspend while switcheroo state is off
  drm/i915: vlv: fix switcheroo/legacy suspend/resume
  drm/i915: propagate error from legacy resume handler
  drm/i915: unify legacy S3 suspend and S4 freeze handlers
  drm/i915: factor out i915_drm_suspend_late
  drm/i915: Emit even number of dwords when emitting LRIs
  drm/i915: Add rotation support for cursor plane (v5)
  drm/i915: Correctly reject invalid flags for wait_ioctl
  drm/i915: use macros to assign mmio access functions
  drm/i915: only run hsw_power_well_post_enable when really needed
  ...

Merge tag 'drm-intel-next-2014-10-03-no-ppgtt' of git://anongit.freedesktop.org/drm-intel into drm-next

Ok, new attempt, this time around with full ppgtt disabled again.

drm-intel-next-2014-10-03:
- first batch of skl stage 1 enabling
- fixes from Rodrigo to the PSR, fbc and sink crc code
- kerneldoc for the frontbuffer tracking code, runtime pm code and the basic
  interrupt enable/disable functions
- smaller stuff all over
drm-intel-next-2014-09-19:
- bunch more i830M fixes from Ville
- full ppgtt now again enabled by default
- more ppgtt fixes from Michel Thierry and Chris Wilson
- plane config work from Gustavo Padovan
- spinlock clarifications
- piles of smaller improvements all over, as usual

* tag 'drm-intel-next-2014-10-03-no-ppgtt' of git://anongit.freedesktop.org/drm-intel: (114 commits)
  Revert "drm/i915: Enable full PPGTT on gen7"
  drm/i915: Update DRIVER_DATE to 20141003
  drm/i915: Remove the duplicated logic between the two shrink phases
  drm/i915: kerneldoc for interrupt enable/disable functions
  drm/i915: Use dev_priv instead of dev in irq setup functions
  drm/i915: s/pm._irqs_disabled/pm.irqs_enabled/
  drm/i915: Clear TX FIFO reset master override bits on chv
  drm/i915: Make sure hardware uses the correct swing margin/deemph bits on chv
  drm/i915: make sink_crc return -EIO on aux read/write failure
  drm/i915: Constify send buffer for intel_dp_aux_ch
  drm/i915: De-magic the PSR AUX message
  drm/i915: Reinstate error level message for non-simulated gpu hangs
  drm/i915: Kerneldoc for intel_runtime_pm.c
  drm/i915: Call runtime_pm_disable directly
  drm/i915: Move intel_display_set_init_power to intel_runtime_pm.c
  drm/i915: Bikeshed rpm functions name a bit.
  drm/i915: Extract intel_runtime_pm.c
  drm/i915: Remove intel_modeset_suspend_hw
  drm/i915: spelling fixes for frontbuffer tracking kerneldoc
  drm/i915: Tighting frontbuffer tracking around flips
  ...

Pull ARM SoC fixes from Olof Johansson:
 "Another week, another small batch of fixes.

  Most of these make zynq, socfpga and sunxi platforms work a bit
  better:

   - due to new requirements for regulators, DWMMC on socfpga broke past
     v3.17
   - SMP spinup fix for socfpga
   - a few DT fixes for zynq
   - another option (FIXED_REGULATOR) for sunxi is needed that used to
     be selected by other options but no longer is.
   - a couple of small DT fixes for at91
   - ...and a couple for i.MX"

* tag 'armsoc-for-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: dts: imx28-evk: Let i2c0 run at 100kHz
  ARM: i.MX6: Fix "emi" clock name typo
  ARM: multi_v7_defconfig: enable CONFIG_MMC_DW_ROCKCHIP
  ARM: sunxi_defconfig: enable CONFIG_REGULATOR_FIXED_VOLTAGE
  ARM: dts: socfpga: Add a 3.3V fixed regulator node
  ARM: dts: socfpga: Fix SD card detect
  ARM: dts: socfpga: rename gpio nodes
  ARM: at91/dt: sam9263: fix PLLB frequencies
  power: reset: at91-reset: fix power down register
  MAINTAINERS: add atmel ssc driver maintainer entry
  arm: socfpga: fix fetching cpu1start_addr for SMP
  ARM: zynq: DT: trivial: Fix mc node
  ARM: zynq: DT: Add cadence watchdog node
  ARM: zynq: DT: Add missing reference for memory-controller
  ARM: zynq: DT: Add missing reference for ADC
  ARM: zynq: DT: Add missing address for L2 pl310
  ARM: zynq: DT: Remove 222 MHz OPP
  ARM: zynq: DT: Fix GEM register area size

Pull vfs updates from Al Viro:
 "overlayfs merge + leak fix for d_splice_alias() failure exits"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  overlayfs: embed middle into overlay_readdir_data
  overlayfs: embed root into overlay_readdir_data
  overlayfs: make ovl_cache_entry->name an array instead of pointer
  overlayfs: don't hold ->i_mutex over opening the real directory
  fix inode leaks on d_splice_alias() failure exits
  fs: limit filesystem stacking depth
  overlay: overlay filesystem documentation
  overlayfs: implement show_options
  overlayfs: add statfs support
  overlay filesystem
  shmem: support RENAME_WHITEOUT
  ext4: support RENAME_WHITEOUT
  vfs: add RENAME_WHITEOUT
  vfs: add whiteout support
  vfs: export check_sticky()
  vfs: introduce clone_private_mount()
  vfs: export __inode_permission() to modules
  vfs: export do_splice_direct() to modules
  vfs: add i_op->dentry_open()

Merge tag 'imx-fixes-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux into fixes

Merge "ARM: imx: fixes for 3.18" from Shawn Guo:

The i.MX fixes for 3.18:
 - Revert one patch which increases I2C bus frequency on imx28-evk
 - Fix a typo on imx6q EIM clock name

* tag 'imx-fixes-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux:
  ARM: dts: imx28-evk: Let i2c0 run at 100kHz
  ARM: i.MX6: Fix "emi" clock name typo
Signed-off-by: Olof Johansson <olof@lixom.net>

Commit 78b81f46 ("ARM: dts: imx28-evk: Run I2C0 at 400kHz") caused issues
when doing the following sequence in loop:

- Boot the kernel
- Perform audio playback
- Reboot the system via 'reboot' command

In many times the audio card cannot be probed, which causes playback to fail.

After restoring to the original i2c0 frequency of 100kHz there is no such
problem anymore.

This reverts commit 78b81f46.

Cc: <stable@vger.kernel.org> # 3.16+
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

Fix a typo error, the "emi" names refer to the eim clocks.

The change fixes typo in EIM and EIM_SLOW pre-output dividers and
selectors clock names. Notably EIM_SLOW clock itself is named correctly.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
[vladimir_zapolskiy@mentor.com: ported to v3.17]
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

same story...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

no sense having it a pointer - all instances have it pointing to
local variable in the same stack frame
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

just use it to serialize the assignment
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull MIPS fixes from Ralf Baechle:
 "This is the first round of fixes and tying up loose ends for MIPS.

   - plenty of fixes for build errors in specific obscure configurations
   - remove redundant code on the Lantiq platform
   - removal of a useless SEAD I2C driver that was causing a build issue
   - fix an earlier TLB exeption handler fix to also work on Octeon.
   - fix ISA level dependencies in FPU emulator's instruction decoding.
   - don't hardcode kernel command line in Octeon software emulator.
   - fix an earlier fix for the Loondson 2 clock setting"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: SEAD3: Fix I2C device registration.
  MIPS: SEAD3: Nuke PIC32 I2C driver.
  MIPS: ftrace: Fix a microMIPS build problem
  MIPS: MSP71xx: Fix build error
  MIPS: Malta: Do not build the malta-amon.c file if CMP is not enabled
  MIPS: Prevent compiler warning from cop2_{save,restore}
  MIPS: Kconfig: Add missing MIPS_CPS dependencies to PM and cpuidle
  MIPS: idle: Remove leftover __pastwait symbol and its references
  MIPS: Sibyte: Include the swarm subdir to the sb1250 LittleSur builds
  MIPS: ptrace.h: Add a missing include
  MIPS: ath79: Fix compilation error when CONFIG_PCI is disabled
  MIPS: MSP71xx: Remove compilation error when CONFIG_MIPS_MT is present
  MIPS: Octeon: Remove special case for simulator command line.
  MIPS: tlbex: Properly fix HUGE TLB Refill exception handler
  MIPS: loongson2_cpufreq: Fix CPU clock rate setting mismerge
  pci: pci-lantiq: remove duplicate check on resource
  MIPS: Lasat: Add missing CONFIG_PROC_FS dependency to PICVUE_PROC
  MIPS: cp1emu: Fix ISA restrictions for cop1x_op instructions

Pull arm64 fixes from Catalin Marinas:

 - enable 48-bit VA space now that KVM has been fixed, together with a
   couple of fixes for pgd allocation alignment and initial memblock
   current_limit.  There is still a dependency on !ARM_SMMU which needs
   to be updated as it uses the page table manipulation macros of the
   host kernel
 - eBPF fixes following changes/conflicts during the merging window
 - Compat types affecting compat_elf_prpsinfo
 - Compilation error on UP builds
 - ASLR fix when /proc/sys/kernel/randomize_va_space == 0
 - DT definitions for CLCD support on ARMv8 model platform

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Fix memblock current_limit with 64K pages and 48-bit VA
  arm64: ASLR: Don't randomise text when randomise_va_space == 0
  arm64: vexpress: Add CLCD support to the ARMv8 model platform
  arm64: Fix compilation error on UP builds
  Documentation/arm64/memory.txt: fix typo
  net: bpf: arm64: minor fix of type in jited
  arm64: bpf: add 'load 64-bit immediate' instruction
  arm64: bpf: add 'shift by register' instructions
  net: bpf: arm64: address randomize and write protect JIT code
  arm64: mm: Correct fixmap pagetable types
  arm64: compat: fix compat types affecting struct compat_elf_prpsinfo
  arm64: Align less than PAGE_SIZE pgds naturally
  arm64: Allow 48-bits VA space without ARM_SMMU

Pull two sparc fixes from David Miller:

 1) Fix boots with gcc-4.9 compiled sparc64 kernels.

 2) Add missing __get_user_pages_fast() on sparc64 to fix hangs on
    futexes used in transparent hugepage areas.

    It's really idiotic to have a weak symbolled fallback that just
    returns zero, and causes this kind of bug.  There should be no
    backup implementation and the link should fail if the architecture
    fails to provide __get_user_pages_fast() and supports transparent
    hugepages.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc64: Implement __get_user_pages_fast().
  sparc64: Fix register corruption in top-most kernel stack frame during boot.