On 03/03/2022 22:42, Matt Roper wrote:
From: Akeem G Abodunrin akeem.g.abodunrin@intel.com
Starting with DG2, preemption can no longer be controlled using userspace on a per-context basis. Instead, the hardware only allows us to enable or disable preemption in a global, system-wide basis. Also, we lose the ability to specify the preemption granularity (such as batch-level vs command-level vs object-level).
As a result of this - for debugging purposes, this patch adds debugfs interface to configure (disable/enable) preemption globally.
Jira: VLK-27831
Cc: Matt Roper matthew.d.roper@intel.com Cc: Prathap Kumar Valsan prathap.kumar.valsan@intel.com Cc: John Harrison john.c.harrison@intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Signed-off-by: Akeem G Abodunrin akeem.g.abodunrin@intel.com Signed-off-by: Matt Roper matthew.d.roper@intel.com
drivers/gpu/drm/i915/gt/intel_gt_regs.h | 3 ++ drivers/gpu/drm/i915/gt/intel_workarounds.c | 2 +- drivers/gpu/drm/i915/i915_debugfs.c | 50 +++++++++++++++++++++ drivers/gpu/drm/i915/i915_drv.h | 3 ++ 4 files changed, 57 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h index 19cd34f24263..21ede1887b9f 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h +++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h @@ -468,6 +468,9 @@ #define VF_PREEMPTION _MMIO(0x83a4) #define PREEMPTION_VERTEX_COUNT REG_GENMASK(15, 0)
+#define GEN12_VFG_PREEMPTION_CHICKEN _MMIO(0x83b4) +#define GEN12_VFG_PREEMPT_CHICKEN_DISABLE REG_BIT(8)
#define GEN8_RC6_CTX_INFO _MMIO(0x8504)
#define GEN12_SQCM _MMIO(0x8724)
diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c index c014b40d2e9f..18dc82f29776 100644 --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c @@ -2310,7 +2310,7 @@ rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal) FF_DOP_CLOCK_GATE_DISABLE); }
- if (IS_GRAPHICS_VER(i915, 9, 12)) {
- if (HAS_PERCTX_PREEMPT_CTRL(i915)) { /* FtrPerCtxtPreemptionGranularityControl:skl,bxt,kbl,cfl,cnl,icl,tgl */ wa_masked_en(wal, GEN7_FF_SLICE_CS_CHICKEN1,
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 747fe9f41e1f..40e6e17e2950 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -571,6 +571,55 @@ static int i915_wa_registers(struct seq_file *m, void *unused) return 0; }
+static void i915_global_preemption_config(struct drm_i915_private *i915,
u32 val)+{
- const u32 bit = GEN12_VFG_PREEMPT_CHICKEN_DISABLE;
- if (val)
intel_uncore_write(&i915->uncore, GEN12_VFG_PREEMPTION_CHICKEN,_MASKED_BIT_DISABLE(bit));- else
intel_uncore_write(&i915->uncore, GEN12_VFG_PREEMPTION_CHICKEN,_MASKED_BIT_ENABLE(bit));
In addition to what Jani suggested some other questions:
Does this setting survive GT reset?
Would intel_reg read/write work?
Can we not add the debugfs file to start with if register is n/a for a platform?
+}
+static int i915_global_preempt_support_get(void *data, u64 *val) +{
- struct drm_i915_private *i915 = data;
- intel_wakeref_t wakeref;
- u32 curr_status = 0;
- if (HAS_PERCTX_PREEMPT_CTRL(i915) || GRAPHICS_VER(i915) < 11)
return -EINVAL;
What is the purpose of the "< 11" condition here? Because HAS_PERCTX_PREEMPT_CTRL is defined as starting on Gen9? Is the 11 arbitrary then or has some deeper meaning?
Regards,
Tvrtko
- with_intel_runtime_pm(&i915->runtime_pm, wakeref)
curr_status = intel_uncore_read(&i915->uncore,GEN12_VFG_PREEMPTION_CHICKEN);- *val = (curr_status & GEN12_VFG_PREEMPT_CHICKEN_DISABLE) ? 0 : 1;
- return 0;
+}
+static int i915_global_preempt_support_set(void *data, u64 val) +{
- struct drm_i915_private *i915 = data;
- intel_wakeref_t wakeref;
- if (HAS_PERCTX_PREEMPT_CTRL(i915) || GRAPHICS_VER(i915) < 11)
return -EINVAL;- with_intel_runtime_pm(&i915->runtime_pm, wakeref)
i915_global_preemption_config(i915, val);- return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(i915_global_preempt_support_fops,
i915_global_preempt_support_get,i915_global_preempt_support_set,"%lld\n");- static int i915_wedged_get(void *data, u64 *val) { struct drm_i915_private *i915 = data;
@@ -765,6 +814,7 @@ static const struct i915_debugfs_files { const struct file_operations *fops; } i915_debugfs_files[] = { {"i915_perf_noa_delay", &i915_perf_noa_delay_fops},
- {"i915_global_preempt_support", &i915_global_preempt_support_fops}, {"i915_wedged", &i915_wedged_fops}, {"i915_gem_drop_caches", &i915_drop_caches_fops}, #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 457bc1993d19..8c3f69c87d36 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1407,6 +1407,9 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915, #define HAS_GUC_DEPRIVILEGE(dev_priv) \ (INTEL_INFO(dev_priv)->has_guc_deprivilege)
+#define HAS_PERCTX_PREEMPT_CTRL(i915) \
- ((GRAPHICS_VER(i915) >= 9) && GRAPHICS_VER_FULL(i915) < IP_VER(12, 55))
- static inline bool run_as_guest(void) { return !hypervisor_is_type(X86_HYPER_NATIVE);