drm/i915/pm: drop intel_suspend_hw()

All intel_suspend_hw() does is clear PCH_LP_PARTITION_LEVEL_DISABLE bit
in SOUTH_DSPCLK_GATE_D for LPT LP. intel_suspend_hw() gets called from
i915_drm_suspend().

However, i915_drm_suspend_late() calls
intel_display_power_suspend_late(), which in turn calls hsw_enable_pc8()
on HSW and BDW. The first thing that does is clear
PCH_LP_PARTITION_LEVEL_DISABLE bit in SOUTH_DSPCLK_GATE_D.

Remove the duplicated clearing of the bit, effectively delaying it from
i915_drm_suspend() to i915_drm_suspend_late(), and remove the
unnecessary intel_suspend_hw() function altogether.

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f732a7922c2450b41169c9b79a80fba97ab00592.1677678803.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_driver.c

@@ -1076,8 +1076,6 @@ static int i915_drm_suspend(struct drm_device *dev)
 
 	intel_suspend_encoders(dev_priv);
 
-	intel_suspend_hw(dev_priv);
-
 	/* Must be called before GGTT is suspended. */
 	intel_dpt_suspend(dev_priv);
 	i915_ggtt_suspend(to_gt(dev_priv)->ggtt);

drivers/gpu/drm/i915/intel_pm.c

@@ -320,16 +320,6 @@ static void lpt_init_clock_gating(struct drm_i915_private *dev_priv)
 			 0, TRANS_CHICKEN1_DP0UNIT_GC_DISABLE);
 }
 
-static void lpt_suspend_hw(struct drm_i915_private *dev_priv)
-{
-	if (HAS_PCH_LPT_LP(dev_priv)) {
-		u32 val = intel_uncore_read(&dev_priv->uncore, SOUTH_DSPCLK_GATE_D);
-
-		val &= ~PCH_LP_PARTITION_LEVEL_DISABLE;
-		intel_uncore_write(&dev_priv->uncore, SOUTH_DSPCLK_GATE_D, val);
-	}
-}
-
 static void gen8_set_l3sqc_credits(struct drm_i915_private *dev_priv,
 				   int general_prio_credits,
 				   int high_prio_credits)
@@ -789,12 +779,6 @@ void intel_init_clock_gating(struct drm_i915_private *dev_priv)
 	dev_priv->clock_gating_funcs->init_clock_gating(dev_priv);
 }
 
-void intel_suspend_hw(struct drm_i915_private *dev_priv)
-{
-	if (HAS_PCH_LPT(dev_priv))
-		lpt_suspend_hw(dev_priv);
-}
-
 static void nop_init_clock_gating(struct drm_i915_private *dev_priv)
 {
 	drm_dbg_kms(&dev_priv->drm,

drivers/gpu/drm/i915/intel_pm.h

@@ -13,7 +13,6 @@ struct intel_crtc_state;
 struct intel_plane_state;
 
 void intel_init_clock_gating(struct drm_i915_private *dev_priv);
-void intel_suspend_hw(struct drm_i915_private *dev_priv);
 void intel_init_clock_gating_hooks(struct drm_i915_private *dev_priv);
 
 #endif /* __INTEL_PM_H__ */