We accidentally point both cfgcr registers for the second shared DPLL to
the same location in i915_reg.h. This results in a lot of hw pipe state
mismatches whenever we try to do a modeset that requires allocating the
DPLL to a CRTC:
[drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in dpll_hw_state.cfgcr1 (expected 0x80000168, found 0x000004a5)
[drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in base.adjusted_mode.crtc_clock (expected 108000, found 49500)
[drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in port_clock (expected 108000, found 49500)
This usually ends up causing blank monitors, since the DPLL never can
get set to the right clock.
Fixes: 086f8e84a0 ("drm/i915: Prefix raw register defines with underscore")
Signed-off-by: Lyude <cpaul@redhat.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1454600601-21900-1-git-send-email-cpaul@redhat.com
(cherry picked from commit da3b891b0f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Our attempts save/restore panel power state in i915_suspend.c are
causing unclaimed register warnings on BXT since the registers for this
platform differ from older platforms.
The big hammer suspend/resume shouldn't be necessary for PP since the
connector/encoder hooks should already handle this. In theory we could
remove this for all platforms, but in practice it's likely that would
cause some regressions since older platforms with LVDS may have
incomplete PP handling. For now we'll leave the PCH save/restore alone
and change the non-PCH branch to only operate on gen <= 4 so that BXT
and future platforms aren't included.
v2: Typo fix: s/||/&&/
v3: Change non-PCH condition to a gen <= 4 test rather than listing
VLV/CHV/BXT as specific platforms to exclude; should be more
future-proof as we add new platforms. (Daniel)
Cc: Vandana Kannan <vandana.kannan@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452102821-17190-1-git-send-email-matthew.d.roper@intel.com
(cherry picked from commit e1ea075423)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
commit 033908aed5
Author: Dave Gordon <david.s.gordon@intel.com>
Date: Thu Dec 10 18:51:23 2015 +0000
drm/i915: mark GEM object pages dirty when mapped & written by the CPU
introduced a check into i915_gem_object_get_dirty_pages() that returned
a NULL pointer when called with a bad object, one that was not backed by
shmemfs. This WARN was too strict as we can work on all struct page
backed objects, and resulted in a WARN + GPF for existing userspace. In
order to differentiate the various types of objects, add a new flags field
to the i915_gem_object_ops struct to describe their capabilities, with
the first flag being whether the object has struct pages.
v2: Drop silly const before an integer in the structure declaration.
Testcase: igt/gem_userptr_blits/relocations
Reported-and-tested-by: Kristian Høgsberg Kristensen <krh@bitplanet.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Kristian Høgsberg Kristensen <krh@bitplanet.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Kristian Høgsberg Kristensen <krh@bitplanet.net>
Tested-by: Michal Winiarski <michal.winiarski@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: 033908aed5 ("drm/i915: mark GEM object pages dirty when mapped & written by the CPU")
Link: http://patchwork.freedesktop.org/patch/msgid/1453487551-16799-1-git-send-email-chris@chris-wilson.co.uk
(cherry picked from commit de4726649b)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Pull drm updates from Dave Airlie:
"This is the main drm pull request for 4.5. I don't think I've missed
anything too major, I'm mostly back at work now but I'll probably get
some sleep in 5 years time.
Summary:
New drivers:
- etnaviv:
GPU driver for the 3D core on the Vivante core used in numerous
ARM boards.
Highlights:
Core:
- Atomic suspend/resume helpers
- Move the headers to using userspace friendlier types.
- Documentation updates
- Lots of struct_mutex removal.
- Bunch of DP MST fixes from AMD.
Panel:
- More DSI helpers
- Support for some new basic panels
i915:
- Basic Kabylake support
- DP link training and detect code refactoring
- fbc/psr fixes
- FIFO underrun fixes
- SDE interrupt handling fixes
- dma-buf/fence support in pageflip path.
- GPU side for MST audio support
radeon/amdgpu:
- Drop UMS support
- GPUVM/Scheduler optimisations
- Initial Powerplay support for Tonga/Fiji/CZ/ST
- ACP audio prerequisites
nouveau:
- GK20a instmem improvements
- PCIE link speed change support
msm:
- DSI support for msm8960/apq8064
tegra:
- Host1X support for Tegra210 SoC
vc4:
- 3D acceleration support
armada:
- Get rid of struct mutex
tda998x:
- Atomic modesetting support
- TMDS clock limitations
omapdrm:
- Atomic modesetting support
- improved TILER performance
rockchip:
- RK3036 VOP support
- Atomic modesetting support
- Synopsys DW MIPI DSI support
exynos:
- Runtime PM support
- of_graph binding for DP panels
- Cleanup of IPP code
- Configurable plane support
- Kernel panic fixes at release time"
* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (711 commits)
drm/fb_cma_helper: Remove implicit call to disable_unused_functions
drm/amdgpu: add missing irq.h include
drm/vmwgfx: Fix a width / pitch mismatch on framebuffer updates
drm/vmwgfx: Fix an incorrect lock check
drm: nouveau: fix nouveau_debugfs_init prototype
drm/nouveau/pci: fix check in nvkm_pcie_set_link
drm/amdgpu: validate duplicates first
drm/amdgpu: move VM page tables to the LRU end on CS v2
drm/ttm: add ttm_bo_move_to_lru_tail function v2
drm/ttm: fix adding foreign BOs to the swap LRU
drm/ttm: fix adding foreign BOs to the LRU during init v2
drm/radeon: use kobj_to_dev()
drm/amdgpu: use kobj_to_dev()
drm/amdgpu/cz: force vce clocks when sclks are forced
drm/amdgpu/cz: force uvd clocks when sclks are forced
drm/amdgpu/cz: add code to enable forcing VCE clocks
drm/amdgpu/cz: add code to enable forcing UVD clocks
drm/amdgpu: fix lost sync_to if scheduler is enabled.
drm/amd/powerplay: fix static checker warning for return meaningless value.
drm/sysfs: use kobj_to_dev()
...
misc i915 fixes all over the place.
* tag 'drm-intel-next-fixes-2016-01-14' of git://anongit.freedesktop.org/drm-intel:
drm/i915/gen9: Set PIN_ZONE_4G end to 4GB - 1 page
drm/i915: Widen return value for reservation_object_wait_timeout_rcu to long.
drm/i915: intel_hpd_init(): Fix suspend/resume reprobing
drm/i915: shut up gen8+ SDE irq dmesg noise, again
drm/i915: Restore inhibiting the load of the default context
drm/i915: Tune down rpm wakelock debug checks
drm/i915: Avoid writing relocs with addresses in non-canonical form
drm/i915: Move Braswell stop_machine GGTT insertion workaround
Since your main drm-next pull isn't out of the door yet I figured I might
as well flush out drm-misc instead of delaying for 4.6. It's really just
random stuff all over, biggest thing probably connector_mask tracking from
Maarten.
* tag 'topic/drm-misc-2016-01-17' of git://anongit.freedesktop.org/drm-intel: (24 commits)
drm/fb_cma_helper: Remove implicit call to disable_unused_functions
drm/sysfs: use kobj_to_dev()
drm/i915: Init power domains early in driver load
drm: Do not set connector->encoder in drivers
apple-gmux: Add initial documentation
drm: move MODULE_PARM_DESC to other file
drm/edid: index CEA/HDMI mode tables using the VIC
drm/atomic: Remove drm_atomic_connectors_for_crtc.
drm/i915: Update connector_mask during readout, v2.
drm: Remove opencoded drm_gem_object_release_handle()
drm: Do not set outparam on error during GEM handle allocation
drm/docs: more leftovers from the big vtable documentation pile
drm/atomic-helper: Reject legacy flips on a disabled pipe
drm/atomic: add connector mask to drm_crtc_state.
drm/tegra: Use __drm_atomic_helper_reset_connector for subclassing connector state, v2.
drm/atomic: Add __drm_atomic_helper_connector_reset, v2.
drm/i915: Set connector_state->connector using the helper.
drm: Use a normal idr allocation for the obj->name
drm: Only bump object-reference count when adding first handle
drm: Balance error path for GEM handle allocation
...
This fixes reprobing of display connectors on resume. After some
talking with danvet on IRC, I learned that calling
drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
connector's status. It turns out this is the actual reason reprobing on
resume hasn't been working (this was observed on a T440s):
- We call hpd_init()
- We check each connector for a couple of things before marking
connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
active encoder. Of course, a disconnected port won't have an
active encoder, so we don't add the flag to any of the
connectors.
- We call drm_helper_hpd_irq_event()
- drm_helper_irq_event() checks each connector for the
DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1,
so we skip reprobing each connector except that one.
In addition, we also now avoid setting connector->polled to
DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is
handled by the mst helpers. This is probably what was originally
intended to happen here.
Changes since V1:
* Use the explanation of the issue as the commit message instead
* Change the title of the commit, since this does more then just stop a
check for an encoder now
* Add "Fixes" line for the patch that introduced this regression
* Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors
Changes since V2:
* Put patch changelog above Signed-off-by
* Follow Daniel Vetter's suggestion for making the code here a bit more
legible
Fixes: 0e32b39cee ("drm/i915: add DP 1.2 MST support (v0.7)")
Cc: stable@vger.kernel.org
Signed-off-by: Lyude <cpaul@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452181408-14777-1-git-send-email-cpaul@redhat.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 07c5191344)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Following a GPU reset, we may leave the context in a poorly defined
state, and reloading from that context will leave the GPU flummoxed. For
secondary contexts, this will lead to that context being banned - but
currently it is also causing the default context to become banned,
leading to turmoil in the shared state.
This is a regression from
commit 6702cf16e0 [v4.1]
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date: Mon Mar 16 16:00:58 2015 +0000
drm/i915: Initialize all contexts
which quietly introduced the removal of the MI_RESTORE_INHIBIT on the
default context.
v2: Mark the global default context as uninitialized on GPU reset so
that the context-local workarounds are reloaded upon re-enabling.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1448630935-27377-1-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: stable@vger.kernel.org
[danvet: This seems to fix a gpu hand on after the first resume,
resulting in any future suspend operation failing with -EIO because
the gpu seems to be in a funky state. Somehow this patch fixes that.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 42f1cae8c0)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
According to PRM, some parts of HW require the addresses to be in
a canonical form, where bits [63:48] == [47]. Let's convert addresses to
canonical form prior to relocating and return converted offsets to
userspace. We also need to make sure that userspace is using addresses
in canonical form in case of softpin.
v2: Whitespace fixup, gen8_canonical_addr description (Chris, Ville)
v3: Rebase on top of softpin, fix a hole in relocate_entry,
s/expect/require (Chris)
v4: Handle softpin in validate_exec_list (Chris)
v5: Convert back to canonical form at copy_to_user time (Chris)
v6: Don't use struct exec_object2 in place of exec_object
v7: Use sign_extend64 for converting to canonical form (Joonas),
reject non-canonical and non-page-aligned offset for softpin (Chris)
v8: Convert back to non-canonical form in a function,
split the test for EXEC_OBJECT_PINNED (Chris)
v9: s/canonial/canonical, drop accidental double newline (Chris)
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1451409892-13708-1-git-send-email-michal.winiarski@intel.com
Testcase: igt/gem_bad_reloc/negative-reloc-blt
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92699
Cc: drm-intel-fixes@lists.freedesktop.org
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 934acce3c0)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
The drm_dp_mst_topology_cbs structures are never modified, so declare them
as const.
Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The total delay of HDMI hotplug detecting with 30ms is sometimes not
enoughtfor HDMI live status up with specific HDMI monitors in BSW platform.
After doing experiments for following monitors, it needs 80ms at least
for those worst cases.
Lenovo L246 1xwA (4 failed, necessary hot-plug delay: 58/40/60/40ms)
Philips HH2AP (9 failed, necessary hot-plug delay: 80/50/50/60/46/40/58/58/39ms)
BENQ ET-0035-N (6 failed, necessary hot-plug delay: 60/50/50/80/80/40ms)
DELL U2713HM (2 failed, necessary hot-plug delay: 58/59ms)
HP HP-LP2475w (5 failed, necessary hot-plug delay: 70/50/40/60/40ms)
It looks like 70-80 ms is BSW platform needs in some bad cases of the
monitors at this end (8 times delay at most). Keep less than 100ms for
HDCP pulse HPD low (with at least 100ms) to respond a plug out.
Reviewed-by: Cooper Chiou <cooper.chiou@intel.com>
Tested-by: Gary Wang <gary.c.wang@intel.com>
Cc: Gavin Hindman <gavin.hindman@intel.com>
Cc: Sonika Jindal <sonika.jindal@intel.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Cc: Shobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: Gary Wang <gary.c.wang@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450858295-12804-1-git-send-email-gary.c.wang@intel.com
Tested-by: Shobhit Kumar <shobhit.kumar@intel.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Fixes: 237ed86c69 ("drm/i915: Check live status before reading edid")
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit f8d03ea005)
[Jani: undo the file mode change of the original commit]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This merges '5b726e06d6e8309e5c9ef4109a32caf27c71dfc8' into drm-next
Just to resolve some merges to make Daniel's life easier.
Signed-off-by: DAve Airlie <airlied@redhat.com>
Atomic changes broke check_digital_port_conflicts(). It needs to look
at the global situation instead of just trying to find a conflict
within the current atomic state.
This bug made my HSW explode spectacularly after I had split the DDI
encoders into separate DP and HDMI encoders. With the fix, things
seem much more solid.
I hope holding the connection_mutex is enough protection that we can
actually walk the connectors even if they're not part of the current
atomic state...
v2: Regenerate the patch so that it actually applies (Jani)
Cc: stable@vger.kernel.org
Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Fixes: 5448a00d3f ("drm/i915: Don't use staged config in check_digital_port_conflicts()")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449764551-12466-1-git-send-email-ville.syrjala@linux.intel.com
(cherry picked from commit 0bff485865)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
- fix atomic watermark recomputation logic (Maarten)
- modeset sequence fixes for LPT (Ville)
- more kbl enabling&prep work (Rodrigo, Wayne)
- first bits for mst audio
- page dirty tracking fixes from Dave Gordon
- new get_eld hook from Takashi, also included in the sound tree
- fixup cursor handling when placed at address 0 (Ville)
- refactor VBT parsing code (Jani)
- rpm wakelock debug infrastructure ( Imre)
- fbdev is pinned again (Chris)
- tune the busywait logic to avoid wasting cpu cycles (Chris)
* tag 'drm-intel-next-2015-12-18' of git://anongit.freedesktop.org/drm-intel: (81 commits)
drm/i915: Update DRIVER_DATE to 20151218
drm/i915/skl: Default to noncoherent access up to F0
drm/i915: Only spin whilst waiting on the current request
drm/i915: Limit the busy wait on requests to 5us not 10ms!
drm/i915: Break busywaiting for requests on pending signals
drm/i915: don't enable autosuspend on platforms without RPM support
drm/i915/backlight: prefer dev_priv over dev pointer
drm/i915: Disable primary plane if we fail to reconstruct BIOS fb (v2)
drm/i915: Pin the ifbdev for the info->system_base GGTT mmapping
drm/i915: Set the map-and-fenceable flag for preallocated objects
drm/i915: mdelay(10) considered harmful
drm/i915: check that we are in an RPM atomic section in GGTT PTE updaters
drm/i915: add support for checking RPM atomic sections
drm/i915: check that we hold an RPM wakelock ref before we put it
drm/i915: add support for checking if we hold an RPM reference
drm/i915: use assert_rpm_wakelock_held instead of opencoding it
drm/i915: add assert_rpm_wakelock_held helper
drm/i915: remove HAS_RUNTIME_PM check from RPM get/put/assert helpers
drm/i915: get a permanent RPM reference on platforms w/o RPM support
drm/i915: refactor RPM disabling due to RC6 being disabled
...
The total delay of HDMI hotplug detecting with 30ms have already
been split into a resolution of 3 retries of 10ms each, for the worst
cases. But it still suffered from only waiting 10ms at most in
intel_hdmi_detect(). This patch corrects it by reading hotplug status
with 4 times at most for 30ms delay.
v2:
- straight up to loop execution for more clear in code readability
- mdelay will replace with msleep by Daniel's new patch
drm/i915: mdelay(10) considered harmful
- suggest to re-evaluate try times for being compatible to old HDMI monitor
Reviewed-by: Cooper Chiou <cooper.chiou@intel.com>
Tested-by: Gary Wang <gary.c.wang@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Gavin Hindman <gavin.hindman@intel.com>
Cc: Sonika Jindal <sonika.jindal@intel.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Gary Wang <gary.c.wang@intel.com>
[danvet: fixup conflict with s/mdelay/msleep/ patch.]
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 61fb3980dd)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Turns out CHV pipe C was glued on somewhat poorly, and there's something
wrong with the cursor. If the cursor straddles the left screen edge,
and is then moved away from the edge or disabled, the pipe will often
underrun. If enough underruns are triggered quickly enough the pipe
will fall over and die (it just scans out a solid color and reports
a constant underrun). We need to turn the disp2d power well off and
on again to recover the pipe.
None of that is very nice for the user, so let's just refuse to place
the cursor in the compromised position. The ddx appears to fall back
to swcursor when the ioctl returns an error, so theoretically there's
no loss of functionality for the user (discounting swcursor bugs).
I suppose most cursors images actually have the hotspot not exactly
at 0,0 so under typical conditions the fallback will in fact kick in
as soon as the cursor touches the left edge of the screen.
Any atomic compositor should anyway be prepared to fall back to
GPU composition when things don't work out, so there should be no
problem with those.
Other things that I tried to solve this include flipping all
display related clock gating knobs I could find, increasing the
minimum gtt alignment all the way up to 512k. I also tried to see
if there are more specific screen coordinates that hit the bug, but
the findings were somewhat inconclusive. Sometimes the failures
happen almost across the whole left edge, sometimes more at the very
top and around the bottom half. I wasn't able to find any real pattern
to these variations, so it seems our only choice is to just refuse
to straddle the left screen edge at all.
Cc: stable@vger.kernel.org
Cc: Jason Plum <max@warheads.net>
Testcase: igt/kms_chv_cursor_fail
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92826
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450459479-16286-1-git-send-email-ville.syrjala@linux.intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit b29ec92c4f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Limit busywaiting only to the request currently being processed by the
GPU. If the request is not currently being processed by the GPU, there
is a very low likelihood of it being completed within the 2 microsecond
spin timeout and so we will just be wasting CPU cycles.
v2: Check for logical inversion when rebasing - we were incorrectly
checking for this request being active, and instead busywaiting for
when the GPU was not yet processing the request of interest.
v3: Try another colour for the seqno names.
v4: Another colour for the function names.
v5: Remove the forced coherency when checking for the active request. On
reflection and plenty of recent experimentation, the issue is not a
cache coherency problem - but an irq/seqno ordering problem (timing issue).
Here, we do not need the w/a to force ordering of the read with an
interrupt.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: "Rogozhkin, Dmitry V" <dmitry.v.rogozhkin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Cc: "Rantala, Valtteri" <valtteri.rantala@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449833608-22125-4-git-send-email-chris@chris-wilson.co.uk
(cherry picked from commit 821485dc2a)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
When waiting for high frequency requests, the finite amount of time
required to set up the irq and wait upon it limits the response rate. By
busywaiting on the request completion for a short while we can service
the high frequency waits as quick as possible. However, if it is a slow
request, we want to sleep as quickly as possible. The tradeoff between
waiting and sleeping is roughly the time it takes to sleep on a request,
on the order of a microsecond. Based on measurements of synchronous
workloads from across big core and little atom, I have set the limit for
busywaiting as 10 microseconds. In most of the synchronous cases, we can
reduce the limit down to as little as 2 miscroseconds, but that leaves
quite a few test cases regressing by factors of 3 and more.
The code currently uses the jiffie clock, but that is far too coarse (on
the order of 10 milliseconds) and results in poor interactivity as the
CPU ends up being hogged by slow requests. To get microsecond resolution
we need to use a high resolution timer. The cheapest of which is polling
local_clock(), but that is only valid on the same CPU. If we switch CPUs
because the task was preempted, we can also use that as an indicator that
the system is too busy to waste cycles on spinning and we should sleep
instead.
__i915_spin_request was introduced in
commit 2def4ad99b [v4.2]
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue Apr 7 16:20:41 2015 +0100
drm/i915: Optimistically spin for the request completion
v2: Drop full u64 for unsigned long - the timer is 32bit wraparound safe,
so we can use native register sizes on smaller architectures. Mention
the approximate microseconds units for elapsed time and add some extra
comments describing the reason for busywaiting.
v3: Raise the limit to 10us
v4: Now 5us.
Reported-by: Jens Axboe <axboe@kernel.dk>
Link: https://lkml.org/lkml/2015/11/12/621
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: "Rogozhkin, Dmitry V" <dmitry.v.rogozhkin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Cc: "Rantala, Valtteri" <valtteri.rantala@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449833608-22125-3-git-send-email-chris@chris-wilson.co.uk
(cherry picked from commit ca5b721e23)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
