Re: [PATCH v4 3/8] drm/i915/skl: Implement enable/disable for Display C5 state.

[Imre Deak <imre.deak@intel.com>]

On to, 2015-04-16 at 14:22 +0530, Animesh Manna wrote:
> From: "A.Sunil Kamath" <sunil.kamath@intel.com>
> 
> This patch just implements the basic enable and disable
> functions of DC5 state which is needed for both SKL and BXT.
> 
> Its important to load respective CSR program before calling
> enable, which anyways will happen as CSR program is executed
> during boot.
> 
> DC5 is a power saving state where hardware dynamically disables
> power well 1 and the CDCLK PLL and saves the associated registers.
> 
> DC5 can be entered when software allows it, power well 2 is
> disabled, and hardware detects that all pipes are disabled
> or pipe A is enabled with PSR active.
> 
> Its better to configure display engine to have power well 2 disabled before
> getting into DC5 enable function. Hence rpm framework will have to
> ensure to check status of power well 2 before calling gen9_enable_dc5.
> 
> Rather dc5 entry criteria should be decided based on power well 2 status.
> If disabled, then call gen9_enable_dc5.
> 
> v2: Replace HAS_ with IS_ check as per Daniel's review comments
> 
> v3: Cleared the bits dc5/dc6 enable of DC_STATE_EN register
> before setting them as per Satheesh's review comments.
> 
> v4: call POSTING_READ for every write to a register to ensure that
> its written immediately.
> 
> v5: Modified as per review comments from Imre.
> - Squashed register definitions into this patch.
> - Finetuned comments and functions.
> 
> v6:
> Avoid redundant writes in gen9_set_dc_state_debugmask_memory_up function.
> 
> v7:
> 1] Rebase to latest.
> 2] Move all runtime PM functions defined in intel_display.c to
>    intel_runtime_pm.c.
> 
> v8: Rebased to drm-intel-nightly. (Animesh)
> 
> Issue: VIZ-2819
> Signed-off-by: A.Sunil Kamath <sunil.kamath@intel.com>
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>

Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
>  drivers/gpu/drm/i915/i915_reg.h         | 11 +++++++++
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 41 +++++++++++++++++++++++++++++++--
>  2 files changed, 50 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 596e8eb..dcb8528 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6792,6 +6792,17 @@ enum skl_disp_power_wells {
>  #define GET_CFG_CR1_REG(id) (DPLL1_CFGCR1 + (id - SKL_DPLL1) * 8)
>  #define GET_CFG_CR2_REG(id) (DPLL1_CFGCR2 + (id - SKL_DPLL1) * 8)
>  
> +/*
> +* SKL DC
> +*/
> +#define  DC_STATE_EN			0x45504
> +#define  DC_STATE_EN_UPTO_DC5		(1<<0)
> +#define  DC_STATE_EN_UPTO_DC6		(2<<0)
> +#define  DC_STATE_EN_UPTO_DC5_DC6_MASK   0x3
> +
> +#define  DC_STATE_DEBUG                  0x45520
> +#define  DC_STATE_DEBUG_MASK_MEMORY_UP	(1<<1)
> +
>  /* 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			(MCHBAR_MIRROR_BASE_SNB + 0x5F0C)
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 23f02a8..466ea69 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -321,14 +321,51 @@ static void hsw_set_power_well(struct drm_i915_private *dev_priv,
>  	SKL_DISPLAY_MISC_IO_POWER_DOMAINS)) |		\
>  	BIT(POWER_DOMAIN_INIT))
>  
> +static void gen9_set_dc_state_debugmask_memory_up(
> +			struct drm_i915_private *dev_priv)
> +{
> +	uint32_t val;
> +
> +	/* The below bit doesn't need to be cleared ever afterwards */
> +	val = I915_READ(DC_STATE_DEBUG);
> +	if (!(val & DC_STATE_DEBUG_MASK_MEMORY_UP)) {
> +		val |= DC_STATE_DEBUG_MASK_MEMORY_UP;
> +		I915_WRITE(DC_STATE_DEBUG, val);
> +		POSTING_READ(DC_STATE_DEBUG);
> +	}
> +}
> +
>  static void gen9_enable_dc5(struct drm_i915_private *dev_priv)
>  {
> -	/* TODO: Implementation to be done. */
> +	struct drm_device *dev = dev_priv->dev;
> +	uint32_t val;
> +
> +	WARN_ON(!IS_GEN9(dev));
> +
> +	DRM_DEBUG_KMS("Enabling DC5\n");
> +
> +	gen9_set_dc_state_debugmask_memory_up(dev_priv);
> +
> +	val = I915_READ(DC_STATE_EN);
> +	val &= ~DC_STATE_EN_UPTO_DC5_DC6_MASK;
> +	val |= DC_STATE_EN_UPTO_DC5;
> +	I915_WRITE(DC_STATE_EN, val);
> +	POSTING_READ(DC_STATE_EN);
>  }
>  
>  static void gen9_disable_dc5(struct drm_i915_private *dev_priv)
>  {
> -	/* TODO: Implementation to be done. */
> +	struct drm_device *dev = dev_priv->dev;
> +	uint32_t val;
> +
> +	WARN_ON(!IS_GEN9(dev));
> +
> +	DRM_DEBUG_KMS("Disabling DC5\n");
> +
> +	val = I915_READ(DC_STATE_EN);
> +	val &= ~DC_STATE_EN_UPTO_DC5;
> +	I915_WRITE(DC_STATE_EN, val);
> +	POSTING_READ(DC_STATE_EN);
>  }
>  
>  static void skl_set_power_well(struct drm_i915_private *dev_priv,


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