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

Changes from v1:
 - Address comments from Paulo
 - implement decode function for SKL/KBL also

Signed-off-by: "Kumar, Mahesh" <mahesh1.ku...@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 170 ++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.h |  14 ++++
 drivers/gpu/drm/i915/i915_reg.h |  38 +++++++++
 3 files changed, 222 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 89d3222..b5f601c 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -979,6 +979,170 @@ static void intel_sanitize_options(struct 
drm_i915_private *dev_priv)
        DRM_DEBUG_DRIVER("use GPU sempahores? %s\n", yesno(i915.semaphores));
 }
 
+static inline void skl_memdev_info_fill(struct memdev_info *info, uint32_t val)
+{
+       uint8_t channel_width, rank;
+
+       info->rank_valid = true;
+       channel_width = (val >> SKL_DRAM_CHANNEL_WIDTH_SHIFT) &
+               SKL_DRAM_CHANNEL_WIDTH_MASK;
+       if (channel_width == SKL_DRAM_WIDTH_1)
+               info->channel_width_bytes = 1;
+       else if (channel_width == SKL_DRAM_WIDTH_2)
+               info->channel_width_bytes = 2;
+       else
+               info->channel_width_bytes = 4;
+
+       rank = (val >> SKL_DRAM_RANK_SHIFT) & SKL_DRAM_RANK_MASK;
+       if (rank == SKL_DRAM_RANK_SINGLE)
+               info->rank = DRAM_RANK_SINGLE;
+       else
+               info->rank = DRAM_RANK_DUAL;
+}
+
+static int
+skl_get_memdev_info(struct drm_i915_private *dev_priv)
+{
+       uint32_t val = 0;
+       uint32_t mem_speed = 0;
+       struct memdev_info *memdev_info = &dev_priv->memdev_info;
+
+       val = I915_READ(SKL_MC_BIOS_DATA_0_0_0_MCHBAR_PCU);
+       mem_speed = div_u64((uint64_t) (val & SKL_REQ_DATA_MASK) *
+                       SKL_MEMORY_FREQ_MULTIPLIER, 1000);
+
+       if (mem_speed == 0)
+               return -EINVAL;
+
+       memdev_info->valid = true;
+       memdev_info->mem_speed_khz = mem_speed;
+       memdev_info->num_channels  = 0;
+
+       memdev_info->rank_valid = false;
+       val = I915_READ(SKL_MAD_DIMM_CH0_0_0_0_MCHBAR_MCMAIN);
+
+       if (val != 0xFFFFFFFF) {
+               memdev_info->num_channels++;
+               skl_memdev_info_fill(memdev_info, val);
+       }
+
+       val = I915_READ(SKL_MAD_DIMM_CH1_0_0_0_MCHBAR_MCMAIN);
+
+       if (val != 0xFFFFFFFF) {
+               memdev_info->num_channels++;
+               if (!memdev_info->rank_valid)
+                       skl_memdev_info_fill(memdev_info, val);
+       }
+
+       if (memdev_info->num_channels == 0)
+               memdev_info->valid = false;
+       return 0;
+}
+
+static int
+bxt_get_memdev_info(struct drm_i915_private *dev_priv)
+{
+       struct memdev_info *memdev_info = &dev_priv->memdev_info;
+       uint32_t dram_channel;
+       uint32_t mem_speed, val;
+       uint8_t num_channel, dram_type;
+       int i;
+
+       val = I915_READ(BXT_P_CR_MC_BIOS_REQ_0_0_0);
+       mem_speed = div_u64((uint64_t) (val & BXT_REQ_DATA_MASK) *
+                       SKL_MEMORY_FREQ_MULTIPLIER, 1000);
+
+       if (mem_speed == 0)
+               return -EINVAL;
+
+       memdev_info->valid = true;
+       memdev_info->mem_speed_khz = mem_speed;
+       dram_type = (val >> BXT_DRAM_TYPE_SHIFT) & BXT_DRAM_TYPE_MASK;
+       dram_channel = (val >> BXT_DRAM_CHANNEL_SHIFT) & BXT_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. In case of single 64 bit
+        * wide DDR3L dimm sets two channel-active bits in
+        * P_CR_MC_BIOS_REQ_0_0_0 register and system with two DDR3L 64bit dimm
+        * will set all four channel-active bits in above register.
+        * In order to get actual number of channels in DDR3L DRAM we need to
+        * device total channel-active bits set by 2.
+        */
+
+       switch (dram_type) {
+       case BXT_DRAM_TYPE_LPDDR3:
+       case BXT_DRAM_TYPE_LPDDR4:
+               memdev_info->channel_width_bytes = 4;
+               memdev_info->num_channels = num_channel;
+               break;
+       case BXT_DRAM_TYPE_DDR3L:
+               memdev_info->channel_width_bytes = 8;
+               memdev_info->num_channels = num_channel / 2;
+               break;
+       default:
+               DRM_DEBUG_KMS("Unknown DRAM type\n");
+               memdev_info->valid = false;
+               return -EINVAL;
+       }
+
+       /*
+        * 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
+        */
+       memdev_info->rank_valid = false;
+       for (i = 0; i < BXT_D_CR_DRP0_DUNIT_MAX; i++) {
+               val = I915_READ(BXT_D_CR_DRP0_DUNIT(i));
+               if (val != 0xFFFFFFFF) {
+                       uint8_t rank;
+
+                       memdev_info->rank_valid = true;
+                       rank = val & BXT_DRAM_RANK_MASK;
+                       if (rank == BXT_DRAM_RANK_SINGLE)
+                               memdev_info->rank = DRAM_RANK_SINGLE;
+                       else if (rank == BXT_DRAM_RANK_DUAL)
+                               memdev_info->rank = DRAM_RANK_DUAL;
+                       else
+                               memdev_info->rank = DRAM_RANK_NONE;
+
+                       break;
+               }
+       }
+       return 0;
+}
+
+static void
+intel_get_memdev_info(struct drm_i915_private *dev_priv)
+{
+       struct memdev_info *memdev_info = &dev_priv->memdev_info;
+       int ret;
+
+       memdev_info->valid = false;
+       if (!IS_GEN9(dev_priv))
+               return;
+
+       if (IS_BROXTON(dev_priv))
+               ret = bxt_get_memdev_info(dev_priv);
+       else
+               ret = skl_get_memdev_info(dev_priv);
+       if (ret)
+               return;
+
+       if (memdev_info->valid) {
+               DRM_DEBUG_DRIVER("DRAM speed-%d Khz total-channels-%d 
channel-width-%d bytes\n",
+                               memdev_info->mem_speed_khz,
+                               memdev_info->num_channels,
+                               memdev_info->channel_width_bytes);
+               if (memdev_info->rank_valid)
+                       DRM_DEBUG_DRIVER("DRAM rank-%s\n",
+                       (memdev_info->rank == DRAM_RANK_DUAL) ?
+                                               "dual" : "single");
+       }
+}
+
+
 /**
  * i915_driver_init_hw - setup state requiring device access
  * @dev_priv: device private
@@ -1082,6 +1246,12 @@ 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_priv);
+
        return 0;
 
 out_ggtt:
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a219a35..adbd9aa 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2057,6 +2057,20 @@ struct drm_i915_private {
                bool distrust_bios_wm;
        } wm;
 
+       struct memdev_info {
+               bool valid;
+               uint32_t mem_speed_khz;
+               uint8_t channel_width_bytes;
+               uint8_t num_channels;
+               bool rank_valid;
+               enum {
+                       DRAM_RANK_NONE = 0,
+                       DRAM_RANK_SINGLE,
+                       DRAM_RANK_DUAL
+               } 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 acc767a..a9c467c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7721,6 +7721,44 @@ enum {
 #define  DC_STATE_DEBUG_MASK_CORES     (1<<0)
 #define  DC_STATE_DEBUG_MASK_MEMORY_UP (1<<1)
 
+#define _MMIO_MCHBAR_PIPE(x, a, b)     _MMIO(MCHBAR_MIRROR_BASE_SNB + _PIPE(x, 
a, b))
+#define BXT_P_CR_MC_BIOS_REQ_0_0_0     _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x7114)
+#define BXT_REQ_DATA_MASK              (0x3F << 0)
+#define BXT_DRAM_TYPE_SHIFT            24
+#define BXT_DRAM_TYPE_MASK             0x7
+#define BXT_DRAM_CHANNEL_SHIFT         12
+#define BXT_DRAM_CHANNEL_MASK          0xF
+
+#define BXT_DRAM_TYPE_LPDDR3           0x1
+#define BXT_DRAM_TYPE_LPDDR4           0x2
+#define BXT_DRAM_TYPE_DDR3L            0x4
+/*
+ * BIOS programs this field of REQ_DATA [5:0] in integer
+ * multiple of 133330 KHz (133.33MHz)
+ */
+#define        SKL_MEMORY_FREQ_MULTIPLIER              0x208D2
+#define BXT_D_CR_DRP0_DUNIT8                   0x1000
+#define BXT_D_CR_DRP0_DUNIT9                   0x1200
+#define BXT_D_CR_DRP0_DUNIT_MAX                        4
+#define BXT_D_CR_DRP0_DUNIT(x) _MMIO_MCHBAR_PIPE(x, BXT_D_CR_DRP0_DUNIT8, 
BXT_D_CR_DRP0_DUNIT9)
+#define BXT_DRAM_RANK_MASK                     0x3
+#define BXT_DRAM_RANK_SINGLE                   0x1
+#define BXT_DRAM_RANK_DUAL                     0x3
+
+#define SKL_MC_BIOS_DATA_0_0_0_MCHBAR_PCU      _MMIO(MCHBAR_MIRROR_BASE_SNB + 
0x5E04)
+#define SKL_REQ_DATA_MASK                      (0xF << 0)
+#define SKL_MAD_DIMM_CH0_0_0_0_MCHBAR_MCMAIN   _MMIO(MCHBAR_MIRROR_BASE_SNB + 
0x500C)
+#define SKL_MAD_DIMM_CH1_0_0_0_MCHBAR_MCMAIN   _MMIO(MCHBAR_MIRROR_BASE_SNB + 
0x5010)
+#define SKL_DRAM_CHANNEL_WIDTH_MASK            0x3
+#define SKL_DRAM_CHANNEL_WIDTH_SHIFT           8
+#define SKL_DRAM_WIDTH_1                       0x0
+#define SKL_DRAM_WIDTH_2                       0x1
+#define SKL_DRAM_WIDTH_4                       0x2
+#define SKL_DRAM_RANK_MASK                     0x1
+#define SKL_DRAM_RANK_SHIFT                    10
+#define SKL_DRAM_RANK_SINGLE                   0x0
+#define SKL_DRAM_RANK_DUAL                     0x1
+
 /* 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)
-- 
2.10.1

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