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authorLinus Torvalds <torvalds@linux-foundation.org>2015-07-24 12:37:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-07-24 12:37:29 -0700
commit077b20537cdd4983cf180b3a3230157f08f16928 (patch)
treee7fd7e730fabbe6339a44d374d388639109476d4
parentb497500069394c5612a4372536353832d64df37b (diff)
parent02bbc4dc6874df0e865aa0977f0046c5c1afd498 (diff)
downloadlinux-077b20537cdd4983cf180b3a3230157f08f16928.tar.gz
Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux
Pull drm fixes from Dave Airlie:
 "Aome amdgpu, one i915, one ttm and one hlcdc, nothing too scary.

  All seems fine for about this time"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/ttm: recognize ARM64 arch in ioprot handler
  drm/amdgpu/cz/dpm: properly report UVD and VCE clock levels
  drm/amdgpu/cz: implement voltage validation properly
  drm/amdgpu: add VCE harvesting instance query
  drm/amdgpu: implement VCE 3.0 harvesting support (v4)
  drm/amdgpu/dce10: Re-set VBLANK interrupt state when enabling a CRTC
  drm/amdgpu/dce11: Re-set VBLANK interrupt state when enabling a CRTC
  drm: Stop resetting connector state to unknown
  drm/i915: Use two 32bit reads for select 64bit REG_READ ioctls
  drm: atmel-hlcdc: fix vblank initial state
-rw-r--r--drivers/gpu/drm/amd/amdgpu/amdgpu.h4
-rw-r--r--drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c1
-rw-r--r--drivers/gpu/drm/amd/amdgpu/cz_dpm.c70
-rw-r--r--drivers/gpu/drm/amd/amdgpu/dce_v10_0.c4
-rw-r--r--drivers/gpu/drm/amd/amdgpu/dce_v11_0.c4
-rw-r--r--drivers/gpu/drm/amd/amdgpu/vce_v3_0.c48
-rw-r--r--drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c1
-rw-r--r--drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c12
-rw-r--r--drivers/gpu/drm/drm_crtc.c5
-rw-r--r--drivers/gpu/drm/i915/intel_uncore.c26
-rw-r--r--drivers/gpu/drm/ttm/ttm_bo_util.c3
-rw-r--r--include/uapi/drm/amdgpu_drm.h2
-rw-r--r--include/uapi/drm/i915_drm.h8
13 files changed, 154 insertions, 34 deletions
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 01657830b470..e9fde72cf038 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1614,6 +1614,9 @@ struct amdgpu_uvd {
 #define AMDGPU_MAX_VCE_HANDLES	16
 #define AMDGPU_VCE_FIRMWARE_OFFSET 256
 
+#define AMDGPU_VCE_HARVEST_VCE0 (1 << 0)
+#define AMDGPU_VCE_HARVEST_VCE1 (1 << 1)
+
 struct amdgpu_vce {
 	struct amdgpu_bo	*vcpu_bo;
 	uint64_t		gpu_addr;
@@ -1626,6 +1629,7 @@ struct amdgpu_vce {
 	const struct firmware	*fw;	/* VCE firmware */
 	struct amdgpu_ring	ring[AMDGPU_MAX_VCE_RINGS];
 	struct amdgpu_irq_src	irq;
+	unsigned		harvest_config;
 };
 
 /*
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index 5533434c7a8f..31ad444c6386 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -459,6 +459,7 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file
 		memcpy(&dev_info.cu_bitmap[0], &cu_info.bitmap[0], sizeof(cu_info.bitmap));
 		dev_info.vram_type = adev->mc.vram_type;
 		dev_info.vram_bit_width = adev->mc.vram_width;
+		dev_info.vce_harvest_config = adev->vce.harvest_config;
 
 		return copy_to_user(out, &dev_info,
 				    min((size_t)size, sizeof(dev_info))) ? -EFAULT : 0;
diff --git a/drivers/gpu/drm/amd/amdgpu/cz_dpm.c b/drivers/gpu/drm/amd/amdgpu/cz_dpm.c
index 1a2d419cbf16..ace870afc7d4 100644
--- a/drivers/gpu/drm/amd/amdgpu/cz_dpm.c
+++ b/drivers/gpu/drm/amd/amdgpu/cz_dpm.c
@@ -494,29 +494,67 @@ static void cz_dpm_fini(struct amdgpu_device *adev)
 	amdgpu_free_extended_power_table(adev);
 }
 
+#define ixSMUSVI_NB_CURRENTVID 0xD8230044
+#define CURRENT_NB_VID_MASK 0xff000000
+#define CURRENT_NB_VID__SHIFT 24
+#define ixSMUSVI_GFX_CURRENTVID  0xD8230048
+#define CURRENT_GFX_VID_MASK 0xff000000
+#define CURRENT_GFX_VID__SHIFT 24
+
 static void
 cz_dpm_debugfs_print_current_performance_level(struct amdgpu_device *adev,
 					       struct seq_file *m)
 {
+	struct cz_power_info *pi = cz_get_pi(adev);
 	struct amdgpu_clock_voltage_dependency_table *table =
 		&adev->pm.dpm.dyn_state.vddc_dependency_on_sclk;
-	u32 current_index =
-		(RREG32_SMC(ixTARGET_AND_CURRENT_PROFILE_INDEX) &
-		TARGET_AND_CURRENT_PROFILE_INDEX__CURR_SCLK_INDEX_MASK) >>
-		TARGET_AND_CURRENT_PROFILE_INDEX__CURR_SCLK_INDEX__SHIFT;
-	u32 sclk, tmp;
-	u16 vddc;
-
-	if (current_index >= NUM_SCLK_LEVELS) {
-		seq_printf(m, "invalid dpm profile %d\n", current_index);
+	struct amdgpu_uvd_clock_voltage_dependency_table *uvd_table =
+		&adev->pm.dpm.dyn_state.uvd_clock_voltage_dependency_table;
+	struct amdgpu_vce_clock_voltage_dependency_table *vce_table =
+		&adev->pm.dpm.dyn_state.vce_clock_voltage_dependency_table;
+	u32 sclk_index = REG_GET_FIELD(RREG32_SMC(ixTARGET_AND_CURRENT_PROFILE_INDEX),
+				       TARGET_AND_CURRENT_PROFILE_INDEX, CURR_SCLK_INDEX);
+	u32 uvd_index = REG_GET_FIELD(RREG32_SMC(ixTARGET_AND_CURRENT_PROFILE_INDEX_2),
+				      TARGET_AND_CURRENT_PROFILE_INDEX_2, CURR_UVD_INDEX);
+	u32 vce_index = REG_GET_FIELD(RREG32_SMC(ixTARGET_AND_CURRENT_PROFILE_INDEX_2),
+				      TARGET_AND_CURRENT_PROFILE_INDEX_2, CURR_VCE_INDEX);
+	u32 sclk, vclk, dclk, ecclk, tmp;
+	u16 vddnb, vddgfx;
+
+	if (sclk_index >= NUM_SCLK_LEVELS) {
+		seq_printf(m, "invalid sclk dpm profile %d\n", sclk_index);
 	} else {
-		sclk = table->entries[current_index].clk;
-		tmp = (RREG32_SMC(ixSMU_VOLTAGE_STATUS) &
-			SMU_VOLTAGE_STATUS__SMU_VOLTAGE_CURRENT_LEVEL_MASK) >>
-			SMU_VOLTAGE_STATUS__SMU_VOLTAGE_CURRENT_LEVEL__SHIFT;
-		vddc = cz_convert_8bit_index_to_voltage(adev, (u16)tmp);
-		seq_printf(m, "power level %d    sclk: %u vddc: %u\n",
-			   current_index, sclk, vddc);
+		sclk = table->entries[sclk_index].clk;
+		seq_printf(m, "%u sclk: %u\n", sclk_index, sclk);
+	}
+
+	tmp = (RREG32_SMC(ixSMUSVI_NB_CURRENTVID) &
+	       CURRENT_NB_VID_MASK) >> CURRENT_NB_VID__SHIFT;
+	vddnb = cz_convert_8bit_index_to_voltage(adev, (u16)tmp);
+	tmp = (RREG32_SMC(ixSMUSVI_GFX_CURRENTVID) &
+	       CURRENT_GFX_VID_MASK) >> CURRENT_GFX_VID__SHIFT;
+	vddgfx = cz_convert_8bit_index_to_voltage(adev, (u16)tmp);
+	seq_printf(m, "vddnb: %u vddgfx: %u\n", vddnb, vddgfx);
+
+	seq_printf(m, "uvd    %sabled\n", pi->uvd_power_gated ? "dis" : "en");
+	if (!pi->uvd_power_gated) {
+		if (uvd_index >= CZ_MAX_HARDWARE_POWERLEVELS) {
+			seq_printf(m, "invalid uvd dpm level %d\n", uvd_index);
+		} else {
+			vclk = uvd_table->entries[uvd_index].vclk;
+			dclk = uvd_table->entries[uvd_index].dclk;
+			seq_printf(m, "%u uvd vclk: %u dclk: %u\n", uvd_index, vclk, dclk);
+		}
+	}
+
+	seq_printf(m, "vce    %sabled\n", pi->vce_power_gated ? "dis" : "en");
+	if (!pi->vce_power_gated) {
+		if (vce_index >= CZ_MAX_HARDWARE_POWERLEVELS) {
+			seq_printf(m, "invalid vce dpm level %d\n", vce_index);
+		} else {
+			ecclk = vce_table->entries[vce_index].ecclk;
+			seq_printf(m, "%u vce ecclk: %u\n", vce_index, ecclk);
+		}
 	}
 }
 
diff --git a/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c b/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
index 6e77964f1b64..e70a26f587a0 100644
--- a/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
@@ -2632,6 +2632,7 @@ static void dce_v10_0_crtc_dpms(struct drm_crtc *crtc, int mode)
 	struct drm_device *dev = crtc->dev;
 	struct amdgpu_device *adev = dev->dev_private;
 	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
+	unsigned type;
 
 	switch (mode) {
 	case DRM_MODE_DPMS_ON:
@@ -2640,6 +2641,9 @@ static void dce_v10_0_crtc_dpms(struct drm_crtc *crtc, int mode)
 		dce_v10_0_vga_enable(crtc, true);
 		amdgpu_atombios_crtc_blank(crtc, ATOM_DISABLE);
 		dce_v10_0_vga_enable(crtc, false);
+		/* Make sure VBLANK interrupt is still enabled */
+		type = amdgpu_crtc_idx_to_irq_type(adev, amdgpu_crtc->crtc_id);
+		amdgpu_irq_update(adev, &adev->crtc_irq, type);
 		drm_vblank_post_modeset(dev, amdgpu_crtc->crtc_id);
 		dce_v10_0_crtc_load_lut(crtc);
 		break;
diff --git a/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c b/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
index 7f7abb0e0be5..dcb402ee048a 100644
--- a/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
@@ -2631,6 +2631,7 @@ static void dce_v11_0_crtc_dpms(struct drm_crtc *crtc, int mode)
 	struct drm_device *dev = crtc->dev;
 	struct amdgpu_device *adev = dev->dev_private;
 	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
+	unsigned type;
 
 	switch (mode) {
 	case DRM_MODE_DPMS_ON:
@@ -2639,6 +2640,9 @@ static void dce_v11_0_crtc_dpms(struct drm_crtc *crtc, int mode)
 		dce_v11_0_vga_enable(crtc, true);
 		amdgpu_atombios_crtc_blank(crtc, ATOM_DISABLE);
 		dce_v11_0_vga_enable(crtc, false);
+		/* Make sure VBLANK interrupt is still enabled */
+		type = amdgpu_crtc_idx_to_irq_type(adev, amdgpu_crtc->crtc_id);
+		amdgpu_irq_update(adev, &adev->crtc_irq, type);
 		drm_vblank_post_modeset(dev, amdgpu_crtc->crtc_id);
 		dce_v11_0_crtc_load_lut(crtc);
 		break;
diff --git a/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c b/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c
index d62c4002e39c..d1064ca3670e 100644
--- a/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/vce_v3_0.c
@@ -35,6 +35,8 @@
 #include "oss/oss_2_0_d.h"
 #include "oss/oss_2_0_sh_mask.h"
 #include "gca/gfx_8_0_d.h"
+#include "smu/smu_7_1_2_d.h"
+#include "smu/smu_7_1_2_sh_mask.h"
 
 #define GRBM_GFX_INDEX__VCE_INSTANCE__SHIFT	0x04
 #define GRBM_GFX_INDEX__VCE_INSTANCE_MASK	0x10
@@ -112,6 +114,10 @@ static int vce_v3_0_start(struct amdgpu_device *adev)
 
 	mutex_lock(&adev->grbm_idx_mutex);
 	for (idx = 0; idx < 2; ++idx) {
+
+		if (adev->vce.harvest_config & (1 << idx))
+			continue;
+
 		if(idx == 0)
 			WREG32_P(mmGRBM_GFX_INDEX, 0,
 				~GRBM_GFX_INDEX__VCE_INSTANCE_MASK);
@@ -190,10 +196,52 @@ static int vce_v3_0_start(struct amdgpu_device *adev)
 	return 0;
 }
 
+#define ixVCE_HARVEST_FUSE_MACRO__ADDRESS     0xC0014074
+#define VCE_HARVEST_FUSE_MACRO__SHIFT       27
+#define VCE_HARVEST_FUSE_MACRO__MASK        0x18000000
+
+static unsigned vce_v3_0_get_harvest_config(struct amdgpu_device *adev)
+{
+	u32 tmp;
+	unsigned ret;
+
+	if (adev->flags & AMDGPU_IS_APU)
+		tmp = (RREG32_SMC(ixVCE_HARVEST_FUSE_MACRO__ADDRESS) &
+		       VCE_HARVEST_FUSE_MACRO__MASK) >>
+			VCE_HARVEST_FUSE_MACRO__SHIFT;
+	else
+		tmp = (RREG32_SMC(ixCC_HARVEST_FUSES) &
+		       CC_HARVEST_FUSES__VCE_DISABLE_MASK) >>
+			CC_HARVEST_FUSES__VCE_DISABLE__SHIFT;
+
+	switch (tmp) {
+	case 1:
+		ret = AMDGPU_VCE_HARVEST_VCE0;
+		break;
+	case 2:
+		ret = AMDGPU_VCE_HARVEST_VCE1;
+		break;
+	case 3:
+		ret = AMDGPU_VCE_HARVEST_VCE0 | AMDGPU_VCE_HARVEST_VCE1;
+		break;
+	default:
+		ret = 0;
+	}
+
+	return ret;
+}
+
 static int vce_v3_0_early_init(void *handle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
+	adev->vce.harvest_config = vce_v3_0_get_harvest_config(adev);
+
+	if ((adev->vce.harvest_config &
+	     (AMDGPU_VCE_HARVEST_VCE0 | AMDGPU_VCE_HARVEST_VCE1)) ==
+	    (AMDGPU_VCE_HARVEST_VCE0 | AMDGPU_VCE_HARVEST_VCE1))
+		return -ENOENT;
+
 	vce_v3_0_set_ring_funcs(adev);
 	vce_v3_0_set_irq_funcs(adev);
 
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index f69b92535505..5ae5c6923128 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -355,6 +355,7 @@ int atmel_hlcdc_crtc_create(struct drm_device *dev)
 		planes->overlays[i]->base.possible_crtcs = 1 << crtc->id;
 
 	drm_crtc_helper_add(&crtc->base, &lcdc_crtc_helper_funcs);
+	drm_crtc_vblank_reset(&crtc->base);
 
 	dc->crtc = &crtc->base;
 
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
index 60b0c13d7ff5..6fad1f9648f3 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
@@ -313,20 +313,20 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev)
 
 	pm_runtime_enable(dev->dev);
 
-	ret = atmel_hlcdc_dc_modeset_init(dev);
+	ret = drm_vblank_init(dev, 1);
 	if (ret < 0) {
-		dev_err(dev->dev, "failed to initialize mode setting\n");
+		dev_err(dev->dev, "failed to initialize vblank\n");
 		goto err_periph_clk_disable;
 	}
 
-	drm_mode_config_reset(dev);
-
-	ret = drm_vblank_init(dev, 1);
+	ret = atmel_hlcdc_dc_modeset_init(dev);
 	if (ret < 0) {
-		dev_err(dev->dev, "failed to initialize vblank\n");
+		dev_err(dev->dev, "failed to initialize mode setting\n");
 		goto err_periph_clk_disable;
 	}
 
+	drm_mode_config_reset(dev);
+
 	pm_runtime_get_sync(dev->dev);
 	ret = drm_irq_install(dev, dc->hlcdc->irq);
 	pm_runtime_put_sync(dev->dev);
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 357bd04a173b..fed748311b92 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -5398,12 +5398,9 @@ void drm_mode_config_reset(struct drm_device *dev)
 		if (encoder->funcs->reset)
 			encoder->funcs->reset(encoder);
 
-	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
-		connector->status = connector_status_unknown;
-
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
 		if (connector->funcs->reset)
 			connector->funcs->reset(connector);
-	}
 }
 EXPORT_SYMBOL(drm_mode_config_reset);
 
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index a6d8a3ee7750..260389acfb77 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1274,10 +1274,12 @@ int i915_reg_read_ioctl(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_reg_read *reg = data;
 	struct register_whitelist const *entry = whitelist;
+	unsigned size;
+	u64 offset;
 	int i, ret = 0;
 
 	for (i = 0; i < ARRAY_SIZE(whitelist); i++, entry++) {
-		if (entry->offset == reg->offset &&
+		if (entry->offset == (reg->offset & -entry->size) &&
 		    (1 << INTEL_INFO(dev)->gen & entry->gen_bitmask))
 			break;
 	}
@@ -1285,23 +1287,33 @@ int i915_reg_read_ioctl(struct drm_device *dev,
 	if (i == ARRAY_SIZE(whitelist))
 		return -EINVAL;
 
+	/* We use the low bits to encode extra flags as the register should
+	 * be naturally aligned (and those that are not so aligned merely
+	 * limit the available flags for that register).
+	 */
+	offset = entry->offset;
+	size = entry->size;
+	size |= reg->offset ^ offset;
+
 	intel_runtime_pm_get(dev_priv);
 
-	switch (entry->size) {
+	switch (size) {
+	case 8 | 1:
+		reg->val = I915_READ64_2x32(offset, offset+4);
+		break;
 	case 8:
-		reg->val = I915_READ64(reg->offset);
+		reg->val = I915_READ64(offset);
 		break;
 	case 4:
-		reg->val = I915_READ(reg->offset);
+		reg->val = I915_READ(offset);
 		break;
 	case 2:
-		reg->val = I915_READ16(reg->offset);
+		reg->val = I915_READ16(offset);
 		break;
 	case 1:
-		reg->val = I915_READ8(reg->offset);
+		reg->val = I915_READ8(offset);
 		break;
 	default:
-		MISSING_CASE(entry->size);
 		ret = -EINVAL;
 		goto out;
 	}
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 882cccdad272..ac6fe40b99f7 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -490,7 +490,8 @@ pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
 	else if (boot_cpu_data.x86 > 3)
 		tmp = pgprot_noncached(tmp);
 #endif
-#if defined(__ia64__) || defined(__arm__) || defined(__powerpc__)
+#if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
+    defined(__powerpc__)
 	if (caching_flags & TTM_PL_FLAG_WC)
 		tmp = pgprot_writecombine(tmp);
 	else
diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
index b6fce900a833..d708a53b8fb1 100644
--- a/include/uapi/drm/amdgpu_drm.h
+++ b/include/uapi/drm/amdgpu_drm.h
@@ -614,6 +614,8 @@ struct drm_amdgpu_info_device {
 	uint32_t vram_type;
 	/** video memory bit width*/
 	uint32_t vram_bit_width;
+	/* vce harvesting instance */
+	uint32_t vce_harvest_config;
 };
 
 struct drm_amdgpu_info_hw_ip {
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 6e1a2ed116cb..db809b722985 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1070,6 +1070,14 @@ struct drm_i915_reg_read {
 	__u64 offset;
 	__u64 val; /* Return value */
 };
+/* Known registers:
+ *
+ * Render engine timestamp - 0x2358 + 64bit - gen7+
+ * - Note this register returns an invalid value if using the default
+ *   single instruction 8byte read, in order to workaround that use
+ *   offset (0x2538 | 1) instead.
+ *
+ */
 
 struct drm_i915_reset_stats {
 	__u32 ctx_id;