From e21dd290881b20c9a37e4a79568841e9ffebeb67 Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@arm.com>
Date: Fri, 16 Aug 2019 10:31:05 +0100
Subject: drm/panfrost: Enable devfreq to work without regulator
Git-commit: e21dd290881b20c9a37e4a79568841e9ffebeb67
Patch-mainline: v5.4-rc1
References: bsc#1152472

If there is no regulator defined for the GPU then still control the
frequency using the supplied clock.

Some boards have clock control but no (direct) control of the regulator.
For example the HiKey960 uses a mailbox protocol to a MCU to control
frequencies and doesn't directly control the voltage. This patch allows
frequency control of the GPU on this system.

Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816093107.30518-1-steven.price@arm.com
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/panfrost/panfrost_devfreq.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
index a7c18bceb7fd..77e1ad24de53 100644
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
@@ -39,7 +39,7 @@ static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
 	 * If frequency scaling from low to high, adjust voltage first.
 	 * If frequency scaling from high to low, adjust frequency first.
 	 */
-	if (old_clk_rate < target_rate) {
+	if (old_clk_rate < target_rate && pfdev->regulator) {
 		err = regulator_set_voltage(pfdev->regulator, target_volt,
 					    target_volt);
 		if (err) {
@@ -58,7 +58,7 @@ static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
 		return err;
 	}
 
-	if (old_clk_rate > target_rate) {
+	if (old_clk_rate > target_rate && pfdev->regulator) {
 		err = regulator_set_voltage(pfdev->regulator, target_volt,
 					    target_volt);
 		if (err)
@@ -136,9 +136,6 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
 	int ret;
 	struct dev_pm_opp *opp;
 
-	if (!pfdev->regulator)
-		return 0;
-
 	ret = dev_pm_opp_of_add_table(&pfdev->pdev->dev);
 	if (ret == -ENODEV) /* Optional, continue without devfreq */
 		return 0;
-- 
2.28.0