[PATCH v3 4/9] drm/i915: Decode system memory bandwidth

["Kumar, Mahesh" <mahesh1.kumar@intel.com>]

From: Mahesh Kumar <mahesh1.kumar@intel.com>

This patch adds support to decode system memory bandwidth
which will be used for arbitrated display memory percentage
calculation in GEN9 based system.

Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 96 +++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.h | 18 ++++++++
 drivers/gpu/drm/i915/i915_reg.h | 25 +++++++++++
 3 files changed, 139 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 02c34d6..0a4f18d 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -973,6 +973,96 @@ static void intel_sanitize_options(struct drm_i915_private *dev_priv)
 	DRM_DEBUG_DRIVER("use GPU sempahores? %s\n", yesno(i915.semaphores));
 }
 
+static void
+intel_get_memdev_info(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	uint32_t val = 0;
+	uint32_t mem_speed = 0;
+	uint8_t dram_type;
+	uint32_t dram_channel;
+	uint8_t num_channel;
+	bool rank_valid = false;
+
+	if (!IS_GEN9(dev_priv))
+		goto exit;
+
+	val = I915_READ(P_CR_MC_BIOS_REQ_0_0_0);
+	mem_speed = div_u64((uint64_t) (val & REQ_DATA_MASK) *
+			MEMORY_FREQ_MULTIPLIER, 1000);
+
+	if (mem_speed == 0)
+		goto exit;
+
+	dev_priv->memdev_info.valid = true;
+	dev_priv->memdev_info.mem_speed = mem_speed;
+	dram_type = (val >> DRAM_TYPE_SHIFT) & DRAM_TYPE_MASK;
+	dram_channel = (val >> DRAM_CHANNEL_SHIFT) & DRAM_CHANNEL_MASK;
+	num_channel = hweight32(dram_channel);
+
+	/*
+	 * The lpddr3 and lpddr4 technologies can have 1-4 channels and the
+	 * channels are 32bits wide; while ddr3l technologies can have 1-2
+	 * channels and the channels are 64 bits wide. But SV team found that in
+	 * case of single 64 bit wide DDR3L dimms two bits were set and system
+	 * with two DDR3L 64bit dimm all four bits were set.
+	 */
+
+	switch (dram_type) {
+	case DRAM_TYPE_LPDDR3:
+	case DRAM_TYPE_LPDDR4:
+		dev_priv->memdev_info.data_width = 4;
+		dev_priv->memdev_info.num_channel = num_channel;
+		break;
+	case DRAM_TYPE_DDR3L:
+		dev_priv->memdev_info.data_width = 8;
+		dev_priv->memdev_info.num_channel = num_channel / 2;
+		break;
+	default:
+		dev_priv->memdev_info.data_width = 4;
+		dev_priv->memdev_info.num_channel = num_channel;
+	}
+
+	/*
+	 * Now read each DUNIT8/9/10/11 to check the rank of each dimms.
+	 * all the dimms should have same rank as in first valid Dimm
+	 */
+#define D_CR_DRP0_DUNIT_INVALID	    0xFFFFFFFF
+
+	dev_priv->memdev_info.rank_valid = true;
+	if (I915_READ(D_CR_DRP0_DUNIT8) != D_CR_DRP0_DUNIT_INVALID) {
+		val = I915_READ(D_CR_DRP0_DUNIT8);
+		rank_valid = true;
+	} else if (I915_READ(D_CR_DRP0_DUNIT9) != D_CR_DRP0_DUNIT_INVALID) {
+		val = I915_READ(D_CR_DRP0_DUNIT9);
+		rank_valid = true;
+	} else if (I915_READ(D_CR_DRP0_DUNIT10) != D_CR_DRP0_DUNIT_INVALID) {
+		val = I915_READ(D_CR_DRP0_DUNIT10);
+		rank_valid = true;
+	} else if (I915_READ(D_CR_DRP0_DUNIT11) != D_CR_DRP0_DUNIT_INVALID) {
+		val = I915_READ(D_CR_DRP0_DUNIT11);
+		rank_valid = true;
+	}
+#undef D_CR_DRP0_DUNIT_INVALID
+
+	if (rank_valid) {
+		dev_priv->memdev_info.rank_valid = true;
+		dev_priv->memdev_info.rank = (val & DRAM_RANK_MASK);
+	}
+
+	DRM_DEBUG_DRIVER("valid:%s speed-%d width-%d num_channel-%d\n",
+		dev_priv->memdev_info.valid ? "true" : "false",
+		dev_priv->memdev_info.mem_speed,
+		dev_priv->memdev_info.data_width,
+		dev_priv->memdev_info.num_channel);
+	DRM_DEBUG_DRIVER("rank_valid:%s rank-%d\n",
+		dev_priv->memdev_info.rank_valid ? "true" : "false",
+		dev_priv->memdev_info.rank);
+	return;
+exit:
+	dev_priv->memdev_info.valid = false;
+}
+
 /**
  * i915_driver_init_hw - setup state requiring device access
  * @dev_priv: device private
@@ -1076,6 +1166,12 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 			DRM_DEBUG_DRIVER("can't enable MSI");
 	}
 
+	/*
+	 * Fill the memdev structure to get the system raw bandwidth
+	 * This will be used by WM algorithm, to implement GEN9 based WA
+	 */
+	intel_get_memdev_info(dev);
+
 	return 0;
 
 out_ggtt:
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 4ec23e5..4313992 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2036,6 +2036,24 @@ struct drm_i915_private {
 		bool distrust_bios_wm;
 	} wm;
 
+	struct {
+		/*
+		 * memory device info
+		 * valid: memory info is valid or not
+		 * mem_speed: memory freq in KHz
+		 * channel_width: Channel width in bytes
+		 * num_channel: total number of channels
+		 * rank: 0-rank disable, 1-Single rank, 2-dual rank
+		 */
+		bool valid;
+		uint32_t mem_speed;
+		uint8_t data_width;
+		uint8_t num_channel;
+		bool rank_valid;
+		uint8_t rank;
+	} memdev_info;
+
+
 	struct i915_runtime_pm pm;
 
 	/* Abstract the submission mechanism (legacy ringbuffer or execlists) away */
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a29d707..b38445c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7716,6 +7716,31 @@ enum {
 #define  DC_STATE_DEBUG_MASK_CORES	(1<<0)
 #define  DC_STATE_DEBUG_MASK_MEMORY_UP	(1<<1)
 
+#define P_CR_MC_BIOS_REQ_0_0_0		_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x7114)
+#define REQ_DATA_MASK			(0x3F << 0)
+#define DRAM_TYPE_SHIFT			24
+#define DRAM_TYPE_MASK			0x7
+#define DRAM_CHANNEL_SHIFT		12
+#define DRAM_CHANNEL_MASK		0xF
+
+#define DRAM_TYPE_LPDDR3		0x1
+#define DRAM_TYPE_LPDDR4		0x2
+#define DRAM_TYPE_DDR3L			0x4
+/*
+ * BIOS programs this field of REQ_DATA [5:0] in integer
+ * multiple of 133330 KHz (133.33MHz)
+ */
+#define MEMORY_FREQ_MULTIPLIER		0x208D2
+#define D_CR_DRP0_DUNIT8		_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x1000)
+#define D_CR_DRP0_DUNIT9		_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x1200)
+#define D_CR_DRP0_DUNIT10		_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x1400)
+#define D_CR_DRP0_DUNIT11		_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x1600)
+#define D_CR_DRP0_RKEN0			(1 << 0)
+#define D_CR_DRP0_RKEN1			(1 << 1)
+#define DRAM_RANK_MASK			0x3
+#define DRAM_SINGLE_RANK		0x1
+#define DRAM_DUAL_RANK			0x3
+
 /* Please see hsw_read_dcomp() and hsw_write_dcomp() before using this register,
  * since on HSW we can't write to it using I915_WRITE. */
 #define D_COMP_HSW			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5F0C)
-- 
2.8.3

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