This is a note to let you know that I've just added the patch titled
drm/i915: Flush WC GGTT only on required platforms
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-flush-wc-ggtt-only-on-required-platforms.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7d7a328d0e8d6edefb7b0d665185d468667588d0 Mon Sep 17 00:00:00 2001
From: Nirmoy Das <nirmoy.das@xxxxxxxxx>
Date: Wed, 18 Oct 2023 11:38:15 +0200
Subject: drm/i915: Flush WC GGTT only on required platforms
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From: Nirmoy Das <nirmoy.das@xxxxxxxxx>
commit 7d7a328d0e8d6edefb7b0d665185d468667588d0 upstream.
gen8_ggtt_invalidate() is only needed for limited set of platforms
where GGTT is mapped as WC. This was added as way to fix WC based GGTT in
commit 0f9b91c754b7 ("drm/i915: flush system agent TLBs on SNB") and
there are no reference in HW docs that forces us to use this on non-WC
backed GGTT.
This can also cause unwanted side-effects on XE_HP platforms where
GFX_FLSH_CNTL_GEN6 is not valid anymore.
v2: Add a func to detect wc ggtt detection (Ville)
v3: Improve commit log and add reference commit (Daniel)
Fixes: d2eae8e98d59 ("drm/i915/dg2: Drop force_probe requirement")
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
Cc: John Harrison <john.c.harrison@xxxxxxxxx>
Cc: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v6.2+
Suggested-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
Reviewed-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20231018093815.1349-1-nirmoy.das@xxxxxxxxx
(cherry picked from commit 81de3e296b10a13e5c9f13172825b0d8d9495c68)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_ggtt.c | 35 ++++++++++++++++++++++++-----------
1 file changed, 24 insertions(+), 11 deletions(-)
--- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
@@ -190,6 +190,21 @@ void gen6_ggtt_invalidate(struct i915_gg
spin_unlock_irq(&uncore->lock);
}
+static bool needs_wc_ggtt_mapping(struct drm_i915_private *i915)
+{
+ /*
+ * On BXT+/ICL+ writes larger than 64 bit to the GTT pagetable range
+ * will be dropped. For WC mappings in general we have 64 byte burst
+ * writes when the WC buffer is flushed, so we can't use it, but have to
+ * resort to an uncached mapping. The WC issue is easily caught by the
+ * readback check when writing GTT PTE entries.
+ */
+ if (!IS_GEN9_LP(i915) && GRAPHICS_VER(i915) < 11)
+ return true;
+
+ return false;
+}
+
static void gen8_ggtt_invalidate(struct i915_ggtt *ggtt)
{
struct intel_uncore *uncore = ggtt->vm.gt->uncore;
@@ -197,8 +212,12 @@ static void gen8_ggtt_invalidate(struct
/*
* Note that as an uncached mmio write, this will flush the
* WCB of the writes into the GGTT before it triggers the invalidate.
+ *
+ * Only perform this when GGTT is mapped as WC, see ggtt_probe_common().
*/
- intel_uncore_write_fw(uncore, GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
+ if (needs_wc_ggtt_mapping(ggtt->vm.i915))
+ intel_uncore_write_fw(uncore, GFX_FLSH_CNTL_GEN6,
+ GFX_FLSH_CNTL_EN);
}
static void guc_ggtt_invalidate(struct i915_ggtt *ggtt)
@@ -902,17 +921,11 @@ static int ggtt_probe_common(struct i915
GEM_WARN_ON(pci_resource_len(pdev, GEN4_GTTMMADR_BAR) != gen6_gttmmadr_size(i915));
phys_addr = pci_resource_start(pdev, GEN4_GTTMMADR_BAR) + gen6_gttadr_offset(i915);
- /*
- * On BXT+/ICL+ writes larger than 64 bit to the GTT pagetable range
- * will be dropped. For WC mappings in general we have 64 byte burst
- * writes when the WC buffer is flushed, so we can't use it, but have to
- * resort to an uncached mapping. The WC issue is easily caught by the
- * readback check when writing GTT PTE entries.
- */
- if (IS_GEN9_LP(i915) || GRAPHICS_VER(i915) >= 11)
- ggtt->gsm = ioremap(phys_addr, size);
- else
+ if (needs_wc_ggtt_mapping(i915))
ggtt->gsm = ioremap_wc(phys_addr, size);
+ else
+ ggtt->gsm = ioremap(phys_addr, size);
+
if (!ggtt->gsm) {
drm_err(&i915->drm, "Failed to map the ggtt page table\n");
return -ENOMEM;
Patches currently in stable-queue which might be from nirmoy.das@xxxxxxxxx are
queue-6.6/drm-i915-flush-wc-ggtt-only-on-required-platforms.patch
queue-6.6/drm-i915-tc-fix-wformat-truncation-in-intel_tc_port_.patch
