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.vet...@intel.com>
> Cc: Damien Lespiau <damien.lesp...@intel.com>
> Cc: Imre Deak <imre.d...@intel.com>
> Cc: Sunil Kamath <sunil.kam...@intel.com>
> Signed-off-by: Animesh Manna <animesh.ma...@intel.com>
> Signed-off-by: Vathsala Nagaraju <vathsala.nagar...@intel.com>
> Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhard...@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
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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