[Intel-gfx] [RFC] drm/i915: add slice shutdown debugfs interface

[Dmitry Rogozhkin]

Slice shutdown override interface (i915_slice_enabled) permits
to power on/off GPGPU slices in Gen8 and Gen9. This is helpful
in performance investigations amd checking scalability across
hw platforms.

Change-Id: I4f2fe5fefb8d1df4519fd0eb58237759c7d1a930
Signed-off-by: Dmitry Rogozhkin <dmitry.v.rogozhkin at intel.com>
CC: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
CC: Zhipeng Gong <zhipeng.gong at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c      | 36 +++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_drv.h          |  1 +
 drivers/gpu/drm/i915/intel_device_info.c |  1 +
 drivers/gpu/drm/i915/intel_lrc.c         |  4 ++--
 4 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index d689e51..977bdb03 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4812,6 +4812,39 @@ static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
 	{"i915_drrs_status", i915_drrs_status, 0},
 	{"i915_rps_boost_info", i915_rps_boost_info, 0},
 };
+
+static int
+i915_slice_enabled_get(void *data, u64 *val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+
+	*val = INTEL_INFO(dev_priv)->sseu.slice_enabled;
+	return 0;
+}
+
+static int
+i915_slice_enabled_set(void *data, u64 val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_device_info *info;
+
+	info = mkwrite_device_info(dev_priv);
+	if (!IS_SKYLAKE(dev_priv) || !info->sseu.has_slice_pg)
+		return -EINVAL;
+
+	if (val > hweight8(info->sseu.slice_mask))
+		return -EINVAL;
+
+	info->sseu.slice_enabled = (u8)val;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(i915_slice_enabled_fops,
+			i915_slice_enabled_get, i915_slice_enabled_set,
+			"%llu\n");
+
 #define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)
 
 static const struct i915_debugfs_files {
@@ -4839,7 +4872,8 @@ static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
 	{"i915_dp_test_type", &i915_displayport_test_type_fops},
 	{"i915_dp_test_active", &i915_displayport_test_active_fops},
 	{"i915_guc_log_control", &i915_guc_log_control_fops},
-	{"i915_hpd_storm_ctl", &i915_hpd_storm_ctl_fops}
+	{"i915_hpd_storm_ctl", &i915_hpd_storm_ctl_fops},
+	{"i915_slice_enabled", &i915_slice_enabled_fops}
 };
 
 int i915_debugfs_register(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index bb6fc1e..7455d43 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -852,6 +852,7 @@ struct sseu_dev_info {
 	u8 has_slice_pg:1;
 	u8 has_subslice_pg:1;
 	u8 has_eu_pg:1;
+	u8 slice_enabled;
 };
 
 static inline unsigned int sseu_subslice_total(const struct sseu_dev_info *sseu)
diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
index 7d01dfe..2eee76b 100644
--- a/drivers/gpu/drm/i915/intel_device_info.c
+++ b/drivers/gpu/drm/i915/intel_device_info.c
@@ -412,6 +412,7 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
 		gen9_sseu_info_init(dev_priv);
 
 	info->has_snoop = !info->has_llc;
+	info->sseu.slice_enabled = hweight8(info->sseu.slice_mask);
 
 	DRM_DEBUG_DRIVER("slice mask: %04x\n", info->sseu.slice_mask);
 	DRM_DEBUG_DRIVER("slice total: %u\n", hweight8(info->sseu.slice_mask));
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 0dc1cc4..bc650df 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1732,7 +1732,7 @@ int logical_xcs_ring_init(struct intel_engine_cs *engine)
 	 * No explicit RPCS request is needed to ensure full
 	 * slice/subslice/EU enablement prior to Gen9.
 	*/
-	if (INTEL_GEN(dev_priv) < 9)
+	if (INTEL_GEN(dev_priv) < 8)
 		return 0;
 
 	/*
@@ -1743,7 +1743,7 @@ int logical_xcs_ring_init(struct intel_engine_cs *engine)
 	*/
 	if (INTEL_INFO(dev_priv)->sseu.has_slice_pg) {
 		rpcs |= GEN8_RPCS_S_CNT_ENABLE;
-		rpcs |= hweight8(INTEL_INFO(dev_priv)->sseu.slice_mask) <<
+		rpcs |= INTEL_INFO(dev_priv)->sseu.slice_enabled <<
 			GEN8_RPCS_S_CNT_SHIFT;
 		rpcs |= GEN8_RPCS_ENABLE;
 	}
-- 
1.8.3.1