From: Abdiel Janulgue <abdiel.janul...@linux.intel.com>
For performance writes over PCIe may not be strictly ordered by default.
This provides an option to expose a kernel configuration option to disable
relaxed ordering and turn on strict ordering instead for debug purposes.
Signed-off-by: Abdiel Janulgue <abdiel.janul...@linux.intel.com>
Signed-off-by: Stuart Summers <stuart.summ...@intel.com>
Cc: Matthew Auld <matthew.a...@intel.com>
---
drivers/gpu/drm/i915/Kconfig.debug | 11 +++++++++++
drivers/gpu/drm/i915/intel_memory_region.c | 12 ++++++++++++
2 files changed, 23 insertions(+)
diff --git a/drivers/gpu/drm/i915/Kconfig.debug
b/drivers/gpu/drm/i915/Kconfig.debug
index 0fb7fd0ef717..65533cbbcb82 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -222,3 +222,14 @@ config DRM_I915_DEBUG_RUNTIME_PM
driver loading, suspend and resume operations.
If in doubt, say "N"
+
+config DRM_I915_PCIE_STRICT_WRITE_ORDERING
+ bool "Enable PCIe strict ordering "
+ depends on DRM_I915
+ default n
+ help
+ Relaxed ordering in writes is enabled by default to improve system
+ performance. Strict ordering can be selected instead to assist in
+ debugging.
+
+ If in doubt, say "N".
diff --git a/drivers/gpu/drm/i915/intel_memory_region.c
b/drivers/gpu/drm/i915/intel_memory_region.c
index cea44ddebe46..043541d409bd 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/intel_memory_region.c
@@ -286,6 +286,18 @@ int intel_memory_regions_hw_probe(struct drm_i915_private
*i915)
{
int err, i;
+ /* All platforms currently have system memory */
+ GEM_BUG_ON(!HAS_REGION(i915, REGION_SMEM));
+
+ if (IS_DGFX(i915)) {
+ if (IS_ENABLED(CONFIG_DRM_I915_PCIE_STRICT_WRITE_ORDERING))
+ pcie_capability_clear_word(i915->drm.pdev,
PCI_EXP_DEVCTL,
+ PCI_EXP_DEVCTL_RELAX_EN);
+ else
+ pcie_capability_set_word(i915->drm.pdev, PCI_EXP_DEVCTL,
+ PCI_EXP_DEVCTL_RELAX_EN);
+ }
+
for (i = 0; i < ARRAY_SIZE(i915->mm.regions); i++) {
struct intel_memory_region *mem = ERR_PTR(-ENODEV);
u16 type, instance;
--
2.26.2
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