Re: [PATCH 1/3] drm/i915/bxt: Enable IPC support

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Tue, 2017-01-31 at 20:27 +0530, Mahesh Kumar wrote:
> This patch adds IPC support for platforms. This patch enables IPC
> only for BXT/KBL platform as for SKL recommendation is to keep it disabled.
> IPC (Isochronous Priority Control) is the hardware feature, which
> dynamically controls 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
> Changes since V2:
>  - Address review comments
>  - Set ipc_enabled flag
> Changes since V3:
>  - move ipc_enabled flag assignment inside intel_ipc_enable function
> Changes since V4:
>  - Re-enable IPC after suspend/resume
> 
> Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c      |  4 +++-
>  drivers/gpu/drm/i915/i915_reg.h      |  1 +
>  drivers/gpu/drm/i915/intel_display.c |  1 +
>  drivers/gpu/drm/i915/intel_drv.h     |  1 +
>  drivers/gpu/drm/i915/intel_pm.c      | 16 ++++++++++++++++
>  5 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index ca168b22ee26..5f3b22946971 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1246,7 +1246,7 @@ int i915_driver_load(struct pci_dev *pdev, const struct
> pci_device_id *ent)
>  
>  	intel_runtime_pm_enable(dev_priv);
>  
> -	dev_priv->ipc_enabled = false;
> +	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",
> @@ -2439,6 +2439,8 @@ static int intel_runtime_resume(struct device *kdev)
>  
>  	enable_rpm_wakeref_asserts(dev_priv);
>  
> +	intel_enable_ipc(dev_priv);
> +
>  	if (ret)
>  		DRM_ERROR("Runtime resume failed, disabling it (%d)\n", ret);
>  	else
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 72f9f36ae5ce..36e0a33f876c 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6466,6 +6466,7 @@ 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_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index 0bf8e1bfbe7e..1aa708b6f55e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -17222,6 +17222,7 @@ void intel_display_resume(struct drm_device *dev)
>  	if (!ret)
>  		ret = __intel_display_resume(dev, state);
>  
> +	intel_enable_ipc(dev_priv);
>  	drm_modeset_drop_locks(&ctx);
>  	drm_modeset_acquire_fini(&ctx);
>  	mutex_unlock(&dev->mode_config.mutex);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 0cec0013ace0..ab7423b0a41b 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1787,6 +1787,7 @@ bool skl_ddb_allocation_overlaps(const struct
> skl_ddb_entry **entries,
>  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 249623d45be0..16e83efa1118 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4667,6 +4667,22 @@ void intel_update_watermarks(struct intel_crtc *crtc)
>  		dev_priv->display.update_wm(crtc);
>  }
>  
> +void intel_enable_ipc(struct drm_i915_private *dev_priv)
> +{
> +	u32 val;
> +
> +	dev_priv->ipc_enabled = false;
> +	if (!(IS_BROXTON(dev_priv) || IS_KABYLAKE(dev_priv)))
> +		return;

Do we want this enabled in Geminilake?

Ander

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