[linux] 03/09: [x86] drm/i915: Mark uneven memory banks on gen4 desktop as unknown swizzling (Closes: #780363)
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commit efc870db168e3e953d8d01dd4820d71ad6e2d3aa
Author: Ben Hutchings <ben at decadent.org.uk>
Date: Sat Dec 12 22:53:37 2015 +0000
[x86] drm/i915: Mark uneven memory banks on gen4 desktop as unknown swizzling (Closes: #780363)
---
debian/changelog | 2 +
...rk-uneven-memory-banks-on-gen4-desktop-as.patch | 115 +++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 118 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index 2715b61..2e9405c 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -13,6 +13,8 @@ linux (4.3.1-1~exp1) UNRELEASED; urgency=medium
* [armel/kirkwood] dts: Fix QNAP TS219 power-off (Closes: #807696)
* [armhf] udeb: Add leds-modules package containing leds-gpio driver
(Closes: #807721)
+ * [x86] drm/i915: Mark uneven memory banks on gen4 desktop as unknown
+ swizzling (Closes: #780363)
-- Ben Hutchings <ben at decadent.org.uk> Wed, 09 Dec 2015 23:20:32 +0000
diff --git a/debian/patches/bugfix/x86/drm-i915-mark-uneven-memory-banks-on-gen4-desktop-as.patch b/debian/patches/bugfix/x86/drm-i915-mark-uneven-memory-banks-on-gen4-desktop-as.patch
new file mode 100644
index 0000000..d430fab
--- /dev/null
+++ b/debian/patches/bugfix/x86/drm-i915-mark-uneven-memory-banks-on-gen4-desktop-as.patch
@@ -0,0 +1,115 @@
+From: Chris Wilson <chris at chris-wilson.co.uk>
+Date: Thu, 19 Nov 2015 09:58:05 +0000
+Subject: drm/i915: Mark uneven memory banks on gen4 desktop as unknown
+ swizzling
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+Origin: http://cgit.freedesktop.org/drm-intel/commit?id=a53f2afb7e3dfc2c7acbb0c015b44783d99d8119
+Bug-Debian: https://bugs.debian.org/780363
+
+We have varied reports of swizzling corruption on gen4 desktop, and
+confirmation that one at least is triggered by uneven memory banks
+(L-shaped memory). The implication is that the swizzling varies between
+the paired channels and the remainder of memory on the single channel. As
+the object then has unpredictable swizzling (it will vary depending on
+exact page allocation and may even change during the object's lifetime as
+the pages are replaced), we have to report to userspace that the swizzling
+is unknown.
+
+However, some existing userspace is buggy when it meets an unknown
+swizzling configuration and so we need to tell another white lie and
+mark the swizzling as NONE but report it as UNKNOWN through the extended
+get-tiling-ioctl. See
+
+commit 5eb3e5a5e11d14f9deb2a4b83555443b69ab9940
+Author: Chris Wilson <chris at chris-wilson.co.uk>
+Date: Sun Jun 28 09:19:26 2015 +0100
+
+ drm/i915: Declare the swizzling unknown for L-shaped configurations
+
+for the previous example where we found that telling the truth to
+userspace just ends up in a world of hurt.
+
+Also since we don't truly know what the swizzling is on the pages, we
+need to keep them pinned to prevent swapping as the reports also
+suggest that some gen4 devices have previously undetected bit17
+swizzling.
+
+v2: Combine unknown + quirk patches to prevent userspace ever seeing
+unknown swizzling through the normal get-tiling-ioctl. Also use the same
+path for the existing uneven bank detection for mobile gen4.
+
+Reported-by: Matti Hämäläinen <ccr at tnsp.org>
+Tested-by: Matti Hämäläinen <ccr at tnsp.org>
+References: https://bugs.freedesktop.org/show_bug.cgi?id=90725
+Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
+Cc: Matti Hämäläinen <ccr at tnsp.org>
+Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
+Cc: Jani Nikula <jani.nikula at intel.com>
+Cc: stable at vger.kernel.org
+Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
+Link: http://patchwork.freedesktop.org/patch/msgid/1447927085-31726-1-git-send-email-chris@chris-wilson.co.uk
+Signed-off-by: Jani Nikula <jani.nikula at intel.com>
+---
+ drivers/gpu/drm/i915/i915_gem_fence.c | 36 ++++++++++++++++++++++++++---------
+ 1 file changed, 27 insertions(+), 9 deletions(-)
+
+--- a/drivers/gpu/drm/i915/i915_gem_fence.c
++++ b/drivers/gpu/drm/i915/i915_gem_fence.c
+@@ -647,11 +647,10 @@ i915_gem_detect_bit_6_swizzle(struct drm
+ }
+
+ /* check for L-shaped memory aka modified enhanced addressing */
+- if (IS_GEN4(dev)) {
+- uint32_t ddc2 = I915_READ(DCC2);
+-
+- if (!(ddc2 & DCC2_MODIFIED_ENHANCED_DISABLE))
+- dev_priv->quirks |= QUIRK_PIN_SWIZZLED_PAGES;
++ if (IS_GEN4(dev) &&
++ !(I915_READ(DCC2) & DCC2_MODIFIED_ENHANCED_DISABLE)) {
++ swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
++ swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
+ }
+
+ if (dcc == 0xffffffff) {
+@@ -680,16 +679,35 @@ i915_gem_detect_bit_6_swizzle(struct drm
+ * matching, which was the case for the swizzling required in
+ * the table above, or from the 1-ch value being less than
+ * the minimum size of a rank.
++ *
++ * Reports indicate that the swizzling actually
++ * varies depending upon page placement inside the
++ * channels, i.e. we see swizzled pages where the
++ * banks of memory are paired and unswizzled on the
++ * uneven portion, so leave that as unknown.
+ */
+- if (I915_READ16(C0DRB3) != I915_READ16(C1DRB3)) {
+- swizzle_x = I915_BIT_6_SWIZZLE_NONE;
+- swizzle_y = I915_BIT_6_SWIZZLE_NONE;
+- } else {
++ if (I915_READ16(C0DRB3) == I915_READ16(C1DRB3)) {
+ swizzle_x = I915_BIT_6_SWIZZLE_9_10;
+ swizzle_y = I915_BIT_6_SWIZZLE_9;
+ }
+ }
+
++ if (swizzle_x == I915_BIT_6_SWIZZLE_UNKNOWN ||
++ swizzle_y == I915_BIT_6_SWIZZLE_UNKNOWN) {
++ /* Userspace likes to explode if it sees unknown swizzling,
++ * so lie. We will finish the lie when reporting through
++ * the get-tiling-ioctl by reporting the physical swizzle
++ * mode as unknown instead.
++ *
++ * As we don't strictly know what the swizzling is, it may be
++ * bit17 dependent, and so we need to also prevent the pages
++ * from being moved.
++ */
++ dev_priv->quirks |= QUIRK_PIN_SWIZZLED_PAGES;
++ swizzle_x = I915_BIT_6_SWIZZLE_NONE;
++ swizzle_y = I915_BIT_6_SWIZZLE_NONE;
++ }
++
+ dev_priv->mm.bit_6_swizzle_x = swizzle_x;
+ dev_priv->mm.bit_6_swizzle_y = swizzle_y;
+ }
diff --git a/debian/patches/series b/debian/patches/series
index d18da73..feaab99 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -97,3 +97,4 @@ bugfix/all/ppp-slip-validate-vj-compression-slot-parameters-com.patch
bugfix/all/btrfs-fix-truncation-of-compressed-and-inlined-exten.patch
bugfix/x86/drm-i915-shut-up-gen8-sde-irq-dmesg-noise.patch
bugfix/arm/arm-dts-kirkwood-fix-qnap-ts219-power-off.patch
+bugfix/x86/drm-i915-mark-uneven-memory-banks-on-gen4-desktop-as.patch
--
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