drm/i915/guc/slpc: Restore efficient freq earlier

This should be done before the soft min/max frequencies are restored.
When we disable the "Ignore efficient frequency" flag, GuC does not
actually bring the requested freq down to RPn.

Specifically, this scenario-

- ignore efficient freq set to true
- reduce min to RPn (from efficient)
- suspend
- resume (includes GuC load, restore soft min/max, restore efficient freq)
- validate min freq has been resored to RPn

This will fail if we didn't first restore(disable, in this case) efficient
freq flag before setting the soft min frequency.

v2: Bring the min freq down to RPn when we disable efficient freq (Rodrigo)
Also made the change to set the min softlimit to RPn at init. Otherwise, we
were storing RPe there.

Link: https://gitlab.freedesktop.org/drm/intel/-/issues/8736
Fixes: 55f9720d ("drm/i915/guc/slpc: Provide sysfs for efficient freq")
Fixes: 95ccf312 ("drm/i915/guc/slpc: Allow SLPC to use efficient frequency")
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230726010044.3280402-1-vinay.belgaumkar@intel.com

drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c

@@ -470,12 +470,19 @@ int intel_guc_slpc_set_ignore_eff_freq(struct intel_guc_slpc *slpc, bool val)
 	ret = slpc_set_param(slpc,
 			     SLPC_PARAM_IGNORE_EFFICIENT_FREQUENCY,
 			     val);
-	if (ret)
+	if (ret) {
 		guc_probe_error(slpc_to_guc(slpc), "Failed to set efficient freq(%d): %pe\n",
 				val, ERR_PTR(ret));
-	else
+	} else {
 		slpc->ignore_eff_freq = val;
 
+		/* Set min to RPn when we disable efficient freq */
+		if (val)
+			ret = slpc_set_param(slpc,
+					     SLPC_PARAM_GLOBAL_MIN_GT_UNSLICE_FREQ_MHZ,
+					     slpc->min_freq);
+	}
+
 	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
 	mutex_unlock(&slpc->lock);
 	return ret;
@@ -602,9 +609,8 @@ static int slpc_set_softlimits(struct intel_guc_slpc *slpc)
 		return ret;
 
 	if (!slpc->min_freq_softlimit) {
-		ret = intel_guc_slpc_get_min_freq(slpc, &slpc->min_freq_softlimit);
-		if (unlikely(ret))
-			return ret;
+		/* Min softlimit is initialized to RPn */
+		slpc->min_freq_softlimit = slpc->min_freq;
 		slpc_to_gt(slpc)->defaults.min_freq = slpc->min_freq_softlimit;
 	} else {
 		return intel_guc_slpc_set_min_freq(slpc,
@@ -755,6 +761,9 @@ int intel_guc_slpc_enable(struct intel_guc_slpc *slpc)
 		return ret;
 	}
 
+	/* Set cached value of ignore efficient freq */
+	intel_guc_slpc_set_ignore_eff_freq(slpc, slpc->ignore_eff_freq);
+
 	/* Revert SLPC min/max to softlimits if necessary */
 	ret = slpc_set_softlimits(slpc);
 	if (unlikely(ret)) {
@@ -765,9 +774,6 @@ int intel_guc_slpc_enable(struct intel_guc_slpc *slpc)
 	/* Set cached media freq ratio mode */
 	intel_guc_slpc_set_media_ratio_mode(slpc, slpc->media_ratio_mode);
 
-	/* Set cached value of ignore efficient freq */
-	intel_guc_slpc_set_ignore_eff_freq(slpc, slpc->ignore_eff_freq);
-
 	return 0;
 }