OMAP3+: PM: DVFS: Scale dependent domains to existing OPP

Currently dependent domain is scaled to:
 - dependent voltage that is got from voltage dependency table.
 - frequency that is got from OPP found for dependent voltage.

OPP for dependent voltage is found by _volt_to_opp() function
which looks for OPP with equal or _greater_ voltage.
So if there is no OPP with exact voltage (or this OPP is disabled),
then frequency from OPP with higher voltage will be used.

As a result device will run at not supported combination of frequency and voltage.
This may lead to instabilities.

This patch scales dependent domain to a correct voltage-frequency tuple,
by using both frequency and voltage from the matched OPP.

Change-Id: Ieb14be32ce2f6f2971ca0530dd077bb445a7e2f7
Signed-off-by: Taras Kondratiuk <taras@ti.com>

1 files changed, 34 insertions, 19 deletions

diff --git a/arch/arm/mach-omap2/dvfs.c b/arch/arm/mach-omap2/dvfs.c
index 44642507eb4..63cb025a441 100644
--- a/arch/arm/mach-omap2/dvfs.c
+++ b/arch/arm/mach-omap2/dvfs.c
@@ -528,7 +528,7 @@ static int _remove_freq_request(struct omap_vdd_dvfs_info *dvfs_info,
  *
  * This runs down the table provided to find the match for main_volt
  * provided and sets up a scale request for the dependent domain
- * for the dependent voltage.
+ * for the dependent OPP.
  *
  * Returns 0 if all went well.
  */
@@ -540,7 +540,7 @@ static int _dep_scan_table(struct device *dev,
 	struct omap_vdd_dvfs_info *tdvfs_info;
 	struct opp *opp;
 	int i, ret;
-	unsigned long dep_volt = 0, new_freq = 0;
+	unsigned long dep_volt = 0, new_dep_volt = 0, new_freq = 0;
 
 	if (!dep_table) {
 		dev_err(dev, "%s: deptable not present for vdd%s\n",
@@ -571,14 +571,6 @@ static int _dep_scan_table(struct device *dev,
 		}
 	}
 
-	/* See if dep_volt is possible for the vdd*/
-	ret = _add_vdd_user(_voltdm_to_dvfs_info(dep_info->_dep_voltdm),
-			dev, dep_volt);
-	if (ret)
-		dev_err(dev, "%s: Failed to add dep to domain %s volt=%ld\n",
-				__func__, dep_info->name, dep_volt);
-
-	/* And also add corresponding freq request */
 	tdvfs_info = _voltdm_to_dvfs_info(dep_info->_dep_voltdm);
 	if (!tdvfs_info) {
 		dev_warn(dev, "%s: no dvfs_info\n",
@@ -594,18 +586,41 @@ static int _dep_scan_table(struct device *dev,
 
 	rcu_read_lock();
 	opp = _volt_to_opp(target_dev, dep_volt);
-	if (!IS_ERR(opp))
+	if (!IS_ERR(opp)) {
+		new_dep_volt = opp_get_voltage(opp);
 		new_freq = opp_get_freq(opp);
+	}
 	rcu_read_unlock();
 
-	if (new_freq) {
-		ret = _add_freq_request(tdvfs_info, dev, target_dev, new_freq);
-		if (ret) {
-			dev_err(target_dev, "%s: freqadd(%s) failed %d[f=%ld,"
-					"v=%ld]\n", __func__, dev_name(dev),
-					i, new_freq, dep_volt);
-			return ret;
-		}
+	if (!new_dep_volt || !new_freq) {
+		dev_err(target_dev, "%s: no valid OPP for voltage %lu\n",
+				__func__, dep_volt);
+		return -ENODATA;
+	}
+
+	/* TODO: In case of _add_vdd_user() failure
+	 * _dep_scan_table() will end up with previous voltage request,
+	 * but without a frequency request.
+	 * System should be left in previous state in case of failure.
+	 * Same issue is present in omap_device_scale() function.
+	 */
+	ret = _add_freq_request(tdvfs_info, dev, target_dev, new_freq);
+	if (ret) {
+		dev_err(target_dev, "%s: freqadd(%s) failed %d"
+				"[f=%ld, v=%ld(%ld)]\n",
+				__func__, dev_name(dev), ret, new_freq,
+				new_dep_volt, dep_volt);
+		return ret;
+	}
+
+	ret = _add_vdd_user(tdvfs_info, dev, new_dep_volt);
+	if (ret) {
+		dev_err(target_dev, "%s: vddadd(%s) failed %d"
+				"[f=%ld, v=%ld(%ld)]\n",
+				__func__, dev_name(dev), ret, new_freq,
+				new_dep_volt, dep_volt);
+		_remove_freq_request(tdvfs_info, dev, target_dev);
+		return ret;
 	}
 
 	return ret;