drm/i915: Abstract the extra JSL/EHL DPLL4 power domain better

Just include the JSL/EHL DPLL4 extra power domain in the dpll_info
struct. This way the same approach could be used by other platforms
as well (should the need arise), and we don't have to sprinkle
platform checks all over the place.

Note that I'm perhaps slightly abusing things here as
power_domain==0 (which is actually POWER_DOMAIN_DISPLAY_CORE) now
indicates that no extra power domain is needed. I suppose using
POWER_DOMAIN_INVALID would be more correct, but then we'd have to
sprinkle that to all the other DPLLs.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231012123522.26045-3-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_dpll_mgr.c

@@ -3838,17 +3838,8 @@ static void combo_pll_enable(struct drm_i915_private *i915,
 {
 	i915_reg_t enable_reg = intel_combo_pll_enable_reg(i915, pll);
 
-	if ((IS_JASPERLAKE(i915) || IS_ELKHARTLAKE(i915)) &&
-	    pll->info->id == DPLL_ID_EHL_DPLL4) {
-
-		/*
-		 * We need to disable DC states when this DPLL is enabled.
-		 * This can be done by taking a reference on DPLL4 power
-		 * domain.
-		 */
-		pll->wakeref = intel_display_power_get(i915,
-						       POWER_DOMAIN_DC_OFF);
-	}
+	if (pll->info->power_domain)
+		pll->wakeref = intel_display_power_get(i915, pll->info->power_domain);
 
 	icl_pll_power_enable(i915, pll, enable_reg);
 
@@ -3946,10 +3937,8 @@ static void combo_pll_disable(struct drm_i915_private *i915,
 
 	icl_pll_disable(i915, pll, enable_reg);
 
-	if ((IS_JASPERLAKE(i915) || IS_ELKHARTLAKE(i915)) &&
-	    pll->info->id == DPLL_ID_EHL_DPLL4)
-		intel_display_power_put(i915, POWER_DOMAIN_DC_OFF,
-					pll->wakeref);
+	if (pll->info->power_domain)
+		intel_display_power_put(i915, pll->info->power_domain, pll->wakeref);
 }
 
 static void tbt_pll_disable(struct drm_i915_private *i915,
@@ -4041,7 +4030,8 @@ static const struct intel_dpll_mgr icl_pll_mgr = {
 static const struct dpll_info ehl_plls[] = {
 	{ .name = "DPLL 0", .funcs = &combo_pll_funcs, .id = DPLL_ID_ICL_DPLL0, },
 	{ .name = "DPLL 1", .funcs = &combo_pll_funcs, .id = DPLL_ID_ICL_DPLL1, },
-	{ .name = "DPLL 4", .funcs = &combo_pll_funcs, .id = DPLL_ID_EHL_DPLL4, },
+	{ .name = "DPLL 4", .funcs = &combo_pll_funcs, .id = DPLL_ID_EHL_DPLL4,
+	  .power_domain = POWER_DOMAIN_DC_OFF, },
 	{}
 };
 
@@ -4369,12 +4359,8 @@ static void readout_dpll_hw_state(struct drm_i915_private *i915,
 
 	pll->on = intel_dpll_get_hw_state(i915, pll, &pll->state.hw_state);
 
-	if ((IS_JASPERLAKE(i915) || IS_ELKHARTLAKE(i915)) &&
-	    pll->on &&
-	    pll->info->id == DPLL_ID_EHL_DPLL4) {
-		pll->wakeref = intel_display_power_get(i915,
-						       POWER_DOMAIN_DC_OFF);
-	}
+	if (pll->on && pll->info->power_domain)
+		pll->wakeref = intel_display_power_get(i915, pll->info->power_domain);
 
 	pll->state.pipe_mask = 0;
 	for_each_intel_crtc(&i915->drm, crtc) {

drivers/gpu/drm/i915/display/intel_dpll_mgr.h

@@ -27,6 +27,7 @@
 
 #include <linux/types.h>
 
+#include "intel_display_power.h"
 #include "intel_wakeref.h"
 
 #define for_each_shared_dpll(__i915, __pll, __i) \
@@ -270,6 +271,11 @@ struct dpll_info {
 	 */
 	enum intel_dpll_id id;
 
+	/**
+	 * @power_domain: extra power domain required by the DPLL
+	 */
+	enum intel_display_power_domain power_domain;
+
 #define INTEL_DPLL_ALWAYS_ON	(1 << 0)
 	/**
 	 * @flags: