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

["Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com>]

On Fri, 2016-09-09 at 13:31 +0530, Kumar, Mahesh wrote:
> 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.

What bits are set? It would be good to clarify the register.

> +	 */
> +
> +	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;

Why is this /2 done here?

> +		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

Should this be Ox2 ?

> +
>  /* 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)

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