Re: [PATCH v4 8/8] drm/i915/bxt: Enable IPC support

[Paulo Zanoni <paulo.r.zanoni@intel.com>]

Em Qui, 2016-10-13 às 16:28 +0530, Kumar, Mahesh escreveu:
> From: Mahesh Kumar <mahesh1.kumar@intel.com>
> 
> This patch adds IPC support for platforms. This patch enables IPC
> only for BXT/KBL platform as for SKL recommendation is to keep is
> disabled.
> IPC (Isochronous Priority Control) is the hardware feature, which
> dynamically controles the memory read priority of Display.
> 
> When IPC is enabled, plane read requests are sent at high priority
> until
> filling above the transition watermark, then the requests are sent at
> lower priority until dropping below the level 0 watermark.
> The lower priority requests allow other memory clients to have better
> memory access. When IPC is disabled, all plane read requests are sent
> at
> high priority.
> 
> Changes since V1:
>  - Remove commandline parameter to disable ipc
>  - Address Paulo's comments
> 

In addition to what others said, we also need the linetime/2 WA if we
want to enable IPC.

Also, see below.

> Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c  |  2 ++
>  drivers/gpu/drm/i915/i915_reg.h  |  1 +
>  drivers/gpu/drm/i915/intel_drv.h |  1 +
>  drivers/gpu/drm/i915/intel_pm.c  | 15 +++++++++++++++
>  4 files changed, 19 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c
> b/drivers/gpu/drm/i915/i915_drv.c
> index b5f601c..58abbaa 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1415,6 +1415,8 @@ int i915_driver_load(struct pci_dev *pdev,
> const struct pci_device_id *ent)
>  
>  	intel_runtime_pm_enable(dev_priv);
>  
> +	intel_enable_ipc(dev_priv);
> +
>  	/* Everything is in place, we can now relax! */
>  	DRM_INFO("Initialized %s %d.%d.%d %s for %s on minor %d\n",
>  		 driver.name, driver.major, driver.minor,
> driver.patchlevel,
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index a9c467c..c9ebf23 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6144,6 +6144,7 @@ enum {
>  #define  DISP_FBC_WM_DIS		(1<<15)
>  #define DISP_ARB_CTL2	_MMIO(0x45004)
>  #define  DISP_DATA_PARTITION_5_6	(1<<6)
> +#define  DISP_IPC_ENABLE		(1<<3)
>  #define DBUF_CTL	_MMIO(0x45008)
>  #define  DBUF_POWER_REQUEST		(1<<31)
>  #define  DBUF_POWER_STATE		(1<<30)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 2c1897b..45b0fa4 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1766,6 +1766,7 @@ void skl_write_plane_wm(struct intel_crtc
> *intel_crtc,
>  uint32_t ilk_pipe_pixel_rate(const struct intel_crtc_state
> *pipe_config);
>  bool ilk_disable_lp_wm(struct drm_device *dev);
>  int sanitize_rc6_option(struct drm_i915_private *dev_priv, int
> enable_rc6);
> +void intel_enable_ipc(struct drm_i915_private *dev_priv);
>  static inline int intel_enable_rc6(void)
>  {
>  	return i915.enable_rc6;
> diff --git a/drivers/gpu/drm/i915/intel_pm.c
> b/drivers/gpu/drm/i915/intel_pm.c
> index 4263212..543aa5d 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4833,6 +4833,21 @@ void intel_update_watermarks(struct drm_crtc
> *crtc)
>  		dev_priv->display.update_wm(crtc);
>  }
>  
> +void intel_enable_ipc(struct drm_i915_private *dev_priv)
> +{
> +	u32 val;
> +
> +	/* enable IPC only for Broxton for now*/
> +	if (!IS_BROXTON(dev_priv) || !IS_KABYLAKE(dev_priv))
> +		return;

This will always return...

> +
> +	val = I915_READ(DISP_ARB_CTL2);
> +
> +	val |= DISP_IPC_ENABLE;
> +
> +	I915_WRITE(DISP_ARB_CTL2, val);
> +}
> +
>  /*
>   * Lock protecting IPS related data structures
>   */
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