linux-kernel - [PATCH v5 4/4] RFC: drm/panfrost: devfreq: Add support for 2 regulators

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Message-Id: <20200306041345.259332-5-drinkcat@chromium.org>
Date:   Fri,  6 Mar 2020 12:13:45 +0800
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Nick Fan <nick.fan@...iatek.com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, hsinyi@...omium.org
Subject: [PATCH v5 4/4] RFC: drm/panfrost: devfreq: Add support for 2 regulators

The Bifrost GPU on MT8183 uses 2 regulators (core and SRAM) for
devfreq, and provides OPP table with 2 sets of voltages.

TODO: This is incomplete as we'll need add support for setting
a pair of voltages as well. I also realized that the out-of-tree
driver has complex logic to ensure voltage delta between the
regulators stays within a specific range, so we'd need to port
that as well.

Signed-off-by: Nicolas Boichat <drinkcat@...omium.org>
---
 drivers/gpu/drm/panfrost/panfrost_devfreq.c | 17 +++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_device.h  |  1 +
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
index 413987038fbfccb..9c0987a3d71c597 100644
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
@@ -79,6 +79,21 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
 	struct devfreq *devfreq;
 	struct thermal_cooling_device *cooling;
 
+	/* If we have 2 regulator, we need an OPP table with 2 voltages. */
+	if (pfdev->comp->num_supplies > 1) {
+		pfdev->devfreq.dev_opp_table =
+			dev_pm_opp_set_regulators(dev,
+					pfdev->comp->supply_names,
+					pfdev->comp->num_supplies);
+		if (IS_ERR(pfdev->devfreq.dev_opp_table)) {
+			ret = PTR_ERR(pfdev->devfreq.dev_opp_table);
+			pfdev->devfreq.dev_opp_table = NULL;
+			dev_err(dev,
+				"Failed to init devfreq opp table: %d\n", ret);
+			return ret;
+		}
+	}
+
 	ret = dev_pm_opp_of_add_table(dev);
 	if (ret == -ENODEV) /* Optional, continue without devfreq */
 		return 0;
@@ -119,6 +134,8 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
 	if (pfdev->devfreq.cooling)
 		devfreq_cooling_unregister(pfdev->devfreq.cooling);
 	dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
+	if (pfdev->devfreq.dev_opp_table)
+		dev_pm_opp_put_regulators(pfdev->devfreq.dev_opp_table);
 }
 
 void panfrost_devfreq_resume(struct panfrost_device *pfdev)
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index c30c719a805940a..5009a8b7c853ea1 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -110,6 +110,7 @@ struct panfrost_device {
 	struct {
 		struct devfreq *devfreq;
 		struct thermal_cooling_device *cooling;
+		struct opp_table *dev_opp_table;
 		ktime_t busy_time;
 		ktime_t idle_time;
 		ktime_t time_last_update;
-- 
2.25.1.481.gfbce0eb801-goog