[linux] 01/01: [x86] drm/i915: Disable PSMI sleep messages on all rings around context switches (Closes: #777231)
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commit 8e6b334fb37c6368f70d9db4ccd842fb84ef51df
Author: Ben Hutchings <ben at decadent.org.uk>
Date: Wed Dec 30 22:31:42 2015 +0000
[x86] drm/i915: Disable PSMI sleep messages on all rings around context switches (Closes: #777231)
---
debian/changelog | 2 +
...sable-psmi-sleep-messages-on-all-rings-ar.patch | 150 +++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 153 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index f510e7b..748c3ea 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -3,6 +3,8 @@ linux (3.16.7-ckt20-2) UNRELEASED; urgency=medium
[ Ben Hutchings ]
* udeb: Add dm-service-time to multipath-modules (Closes: #806131)
* xfs: allow inode allocations in post-growfs disk space (Closes: #802885)
+ * [x86] drm/i915: Disable PSMI sleep messages on all rings around context
+ switches (Closes: #777231)
[ Aurelien Jarno ]
* [mips*] Add support for MIPS 5KE CPU.
diff --git a/debian/patches/bugfix/x86/drm-i915-disable-psmi-sleep-messages-on-all-rings-ar.patch b/debian/patches/bugfix/x86/drm-i915-disable-psmi-sleep-messages-on-all-rings-ar.patch
new file mode 100644
index 0000000..95d58e1
--- /dev/null
+++ b/debian/patches/bugfix/x86/drm-i915-disable-psmi-sleep-messages-on-all-rings-ar.patch
@@ -0,0 +1,150 @@
+From: Chris Wilson <chris at chris-wilson.co.uk>
+Date: Tue, 16 Dec 2014 10:02:27 +0000
+Subject: drm/i915: Disable PSMI sleep messages on all rings around context
+ switches
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+Origin: https://git.kernel.org/linus/2c550183476dfa25641309ae9a28d30feed14379
+
+There exists a current workaround to prevent a hang on context switch
+should the ring go to sleep in the middle of the restore,
+WaProgramMiArbOnOffAroundMiSetContext (applicable to all gen7+). In
+spite of disabling arbitration (which prevents the ring from powering
+down during the critical section) we were still hitting hangs that had
+the hallmarks of the known erratum. That is we are still seeing hangs
+"on the last instruction in the context restore". By comparing -nightly
+(broken) with requests (working), we were able to deduce that it was the
+semaphore LRI cross-talk that reproduced the original failure. The key
+was that requests implemented deferred semaphore signalling, and
+disabling that, i.e. emitting the semaphore signal to every other ring
+after every batch restored the frequent hang. Explicitly disabling PSMI
+sleep on the RCS ring was insufficient, all the rings had to be awake to
+prevent the hangs. Fortunately, we can reduce the wakelock to the
+MI_SET_CONTEXT operation itself, and so should be able to limit the extra
+power implications.
+
+Since the MI_ARB_ON_OFF workaround is listed for all gen7 and above
+products, we should apply this extra hammer for all of the same
+platforms despite so far that we have only been able to reproduce the
+hang on certain ivb and hsw models. The last question is whether we want
+to always use the extra hammer or only when we know semaphores are in
+operation. At the moment, we only use LRI on non-RCS rings for
+semaphores, but that may change in the future with the possibility of
+reintroducing this bug under subtle conditions.
+
+v2: Make it explicit that the PSMI LRI are an extension to the original
+workaround for the other rings.
+v3: Bikeshedding variable names and whitespacing
+
+Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=80660
+Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83677
+Cc: Simon Farnsworth <simon at farnz.org.uk>
+Cc: Daniel Vetter <daniel at ffwll.ch>
+Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
+Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
+Tested-by: Peter Frühberger <fritsch at xbmc.org>
+Reviewed-by: Daniel Vetter <daniel at ffwll.ch>
+Cc: stable at vger.kernel.org
+Signed-off-by: Jani Nikula <jani.nikula at intel.com>
+[bwh: Backported to 3.16: adjust context]
+---
+ drivers/gpu/drm/i915/i915_gem_context.c | 48 +++++++++++++++++++++++++++------
+ drivers/gpu/drm/i915/i915_reg.h | 2 ++
+ 2 files changed, 42 insertions(+), 8 deletions(-)
+
+--- a/drivers/gpu/drm/i915/i915_gem_context.c
++++ b/drivers/gpu/drm/i915/i915_gem_context.c
+@@ -545,7 +545,12 @@ mi_set_context(struct intel_engine_cs *r
+ struct intel_context *new_context,
+ u32 hw_flags)
+ {
+- int ret;
++ const int num_rings =
++ /* Use an extended w/a on ivb+ if signalling from other rings */
++ i915_semaphore_is_enabled(ring->dev) ?
++ hweight32(INTEL_INFO(ring->dev)->ring_mask) - 1 :
++ 0;
++ int len, i, ret;
+
+ /* w/a: If Flush TLB Invalidation Mode is enabled, driver must do a TLB
+ * invalidation prior to MI_SET_CONTEXT. On GEN6 we don't set the value
+@@ -558,15 +563,31 @@ mi_set_context(struct intel_engine_cs *r
+ return ret;
+ }
+
+- ret = intel_ring_begin(ring, 6);
++
++ len = 4;
++ if (INTEL_INFO(ring->dev)->gen >= 7)
++ len += 2 + (num_rings ? 4*num_rings + 2 : 0);
++
++ ret = intel_ring_begin(ring, len);
+ if (ret)
+ return ret;
+
+ /* WaProgramMiArbOnOffAroundMiSetContext:ivb,vlv,hsw,bdw,chv */
+- if (INTEL_INFO(ring->dev)->gen >= 7)
++ if (INTEL_INFO(ring->dev)->gen >= 7) {
+ intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_DISABLE);
+- else
+- intel_ring_emit(ring, MI_NOOP);
++ if (num_rings) {
++ struct intel_engine_cs *signaller;
++
++ intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(num_rings));
++ for_each_ring(signaller, to_i915(ring->dev), i) {
++ if (signaller == ring)
++ continue;
++
++ intel_ring_emit(ring, RING_PSMI_CTL(signaller->mmio_base));
++ intel_ring_emit(ring, _MASKED_BIT_ENABLE(GEN6_PSMI_SLEEP_MSG_DISABLE));
++ }
++ }
++ }
+
+ intel_ring_emit(ring, MI_NOOP);
+ intel_ring_emit(ring, MI_SET_CONTEXT);
+@@ -581,10 +602,21 @@ mi_set_context(struct intel_engine_cs *r
+ */
+ intel_ring_emit(ring, MI_NOOP);
+
+- if (INTEL_INFO(ring->dev)->gen >= 7)
++ if (INTEL_INFO(ring->dev)->gen >= 7) {
++ if (num_rings) {
++ struct intel_engine_cs *signaller;
++
++ intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(num_rings));
++ for_each_ring(signaller, to_i915(ring->dev), i) {
++ if (signaller == ring)
++ continue;
++
++ intel_ring_emit(ring, RING_PSMI_CTL(signaller->mmio_base));
++ intel_ring_emit(ring, _MASKED_BIT_DISABLE(GEN6_PSMI_SLEEP_MSG_DISABLE));
++ }
++ }
+ intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE);
+- else
+- intel_ring_emit(ring, MI_NOOP);
++ }
+
+ intel_ring_advance(ring);
+
+--- a/drivers/gpu/drm/i915/i915_reg.h
++++ b/drivers/gpu/drm/i915/i915_reg.h
+@@ -978,6 +978,7 @@ enum punit_power_well {
+ #define GEN6_VERSYNC (RING_SYNC_1(VEBOX_RING_BASE))
+ #define GEN6_VEVSYNC (RING_SYNC_2(VEBOX_RING_BASE))
+ #define GEN6_NOSYNC 0
++#define RING_PSMI_CTL(base) ((base)+0x50)
+ #define RING_MAX_IDLE(base) ((base)+0x54)
+ #define RING_HWS_PGA(base) ((base)+0x80)
+ #define RING_HWS_PGA_GEN6(base) ((base)+0x2080)
+@@ -1301,6 +1302,7 @@ enum punit_power_well {
+ #define GEN6_BLITTER_FBC_NOTIFY (1<<3)
+
+ #define GEN6_RC_SLEEP_PSMI_CONTROL 0x2050
++#define GEN6_PSMI_SLEEP_MSG_DISABLE (1 << 0)
+ #define GEN8_RC_SEMA_IDLE_MSG_DISABLE (1 << 12)
+ #define GEN8_FF_DOP_CLOCK_GATE_DISABLE (1<<10)
+
diff --git a/debian/patches/series b/debian/patches/series
index d9579f5..b1daec2 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -652,3 +652,4 @@ debian/af_unix-avoid-abi-changes.patch
bugfix/all/btrfs-fix-truncation-of-compressed-and-inlined-exten.patch
bugfix/all/net-add-validation-for-the-socket-syscall-protocol.patch
bugfix/all/xfs-allow-inode-allocations-in-post-growfs-disk-spac.patch
+bugfix/x86/drm-i915-disable-psmi-sleep-messages-on-all-rings-ar.patch
--
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