Re: [SKL-DMC-BUGFIX 2/5] drm/i915/skl: Making DC6 entry is the last call in suspend flow.

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Aug 03, 2015 at 09:55:33PM +0530, Animesh Manna wrote:
> Mmio register access after dc6/dc5 entry is not allowed when
> DC6 power states are enabled according to bspec (bspec-id 0527),
> so enabling dc6 as the last call in suspend flow.
> 
> v1: Initial version.
> 
> v2: commit message updated based on comment from Vathsala.
> 
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Damien Lespiau <damien.lespiau@intel.com>
> Cc: Imre Deak <imre.deak@intel.com>
> Cc: Sunil Kamath <sunil.kamath@intel.com>
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> Signed-off-by: Vathsala Nagaraju <vathsala.nagaraju@intel.com>
> Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c         | 12 ++++++------
>  drivers/gpu/drm/i915/intel_drv.h        |  2 ++
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 33 ++++++++-------------------------
>  3 files changed, 16 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 0d6775a..e1d0102 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1017,14 +1017,11 @@ static int skl_suspend_complete(struct drm_i915_private *dev_priv)
>  {
>  	/* Enabling DC6 is not a hard requirement to enter runtime D3 */
>  
> -	/*
> -	 * This is to ensure that CSR isn't identified as loaded before
> -	 * CSR-loading program is called during runtime-resume.
> -	 */
> -	intel_csr_load_status_set(dev_priv, FW_UNINITIALIZED);

Seems like an unrelated hunk. Separate patch (in the dmc loader rework
series) or an explanation why we need this.

> -
>  	skl_uninit_cdclk(dev_priv);
>  
> +	if (intel_csr_load_status_get(dev_priv) == FW_LOADED)
> +		skl_enable_dc6(dev_priv);
> +
>  	return 0;
>  }
>  
> @@ -1071,6 +1068,9 @@ static int skl_resume_prepare(struct drm_i915_private *dev_priv)
>  {
>  	struct drm_device *dev = dev_priv->dev;
>  
> +	if (intel_csr_load_status_get(dev_priv) == FW_LOADED)
> +		skl_disable_dc6(dev_priv);
> +
>  	skl_init_cdclk(dev_priv);
>  	intel_csr_load_program(dev);
>  
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 47cef0e..06f346f 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1117,6 +1117,8 @@ void bxt_enable_dc9(struct drm_i915_private *dev_priv);
>  void bxt_disable_dc9(struct drm_i915_private *dev_priv);
>  void skl_init_cdclk(struct drm_i915_private *dev_priv);
>  void skl_uninit_cdclk(struct drm_i915_private *dev_priv);
> +void skl_enable_dc6(struct drm_i915_private *dev_priv);
> +void skl_disable_dc6(struct drm_i915_private *dev_priv);
>  void intel_dp_get_m_n(struct intel_crtc *crtc,
>  		      struct intel_crtc_state *pipe_config);
>  void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set m_n);
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 6393b76..c660245 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -532,7 +532,7 @@ static void assert_can_disable_dc6(struct drm_i915_private *dev_priv)
>  		"DC6 already programmed to be disabled.\n");
>  }
>  
> -static void skl_enable_dc6(struct drm_i915_private *dev_priv)
> +void skl_enable_dc6(struct drm_i915_private *dev_priv)
>  {
>  	uint32_t val;
>  
> @@ -549,7 +549,7 @@ static void skl_enable_dc6(struct drm_i915_private *dev_priv)
>  	POSTING_READ(DC_STATE_EN);
>  }
>  
> -static void skl_disable_dc6(struct drm_i915_private *dev_priv)
> +void skl_disable_dc6(struct drm_i915_private *dev_priv)
>  {
>  	uint32_t val;

Everything above seems to roughly be matching your patch description, but
not perfectly: You talk about suspend flow but also touch resume flow.

But the hunks below are completely unexplained magic afaict. Either this
needs a separate patch or it needs seriously more explanation of what's
going on.

>  
> @@ -610,10 +610,10 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
>  				!I915_READ(HSW_PWR_WELL_BIOS),
>  				"Invalid for power well status to be enabled, unless done by the BIOS, \
>  				when request is to disable!\n");
> -			if ((GEN9_ENABLE_DC5(dev) || SKL_ENABLE_DC6(dev)) &&
> -				power_well->data == SKL_DISP_PW_2) {
> +			if (power_well->data == SKL_DISP_PW_2) {
> +				if (GEN9_ENABLE_DC5(dev))
> +					gen9_disable_dc5(dev_priv);
>  				if (SKL_ENABLE_DC6(dev)) {
> -					skl_disable_dc6(dev_priv);
>  					/*
>  					 * DDI buffer programming unnecessary during driver-load/resume
>  					 * as it's already done during modeset initialization then.
> @@ -621,8 +621,6 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
>  					 */
>  					if (!dev_priv->power_domains.initializing)
>  						intel_prepare_ddi(dev);
> -				} else {
> -					gen9_disable_dc5(dev_priv);
>  				}
>  			}
>  			I915_WRITE(HSW_PWR_WELL_DRIVER, tmp | req_mask);
> @@ -642,24 +640,9 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
>  			POSTING_READ(HSW_PWR_WELL_DRIVER);
>  			DRM_DEBUG_KMS("Disabling %s\n", power_well->name);
>  
> -			if ((GEN9_ENABLE_DC5(dev) || SKL_ENABLE_DC6(dev)) &&
> -				power_well->data == SKL_DISP_PW_2) {
> -				enum csr_state state;
> -				/* TODO: wait for a completion event or
> -				 * similar here instead of busy
> -				 * waiting using wait_for function.
> -				 */
> -				wait_for((state = intel_csr_load_status_get(dev_priv)) !=
> -						FW_UNINITIALIZED, 1000);
> -				if (state != FW_LOADED)
> -					DRM_ERROR("CSR firmware not ready (%d)\n",
> -							state);
> -				else
> -					if (SKL_ENABLE_DC6(dev))
> -						skl_enable_dc6(dev_priv);
> -					else
> -						gen9_enable_dc5(dev_priv);
> -			}
> +			if (GEN9_ENABLE_DC5(dev) &&
> +				power_well->data == SKL_DISP_PW_2)
> +					gen9_enable_dc5(dev_priv);
>  		}
>  	}
>  
> -- 
> 2.0.2
> 
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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