[PATCH v2 5/6] drm/panfrost: Implement ability to turn on/off regulators in suspend

[AngeloGioacchino Del Regno]

Some platforms/SoCs can power off the GPU entirely by completely cutting
off power, greatly enhancing battery time during system suspend: add a
new pm_feature GPU_PM_VREG_OFF to allow turning off the GPU regulators
during full suspend only on selected platforms.

Signed-off-by: AngeloGioacchino Del Regno 
<angelogioacchino.delre...@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_device.c | 19 ++++++++++++++++++-
 drivers/gpu/drm/panfrost/panfrost_device.h |  2 ++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c 
b/drivers/gpu/drm/panfrost/panfrost_device.c
index 2022ed76a620..51b22eb0971d 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -431,10 +431,21 @@ static int panfrost_device_resume(struct device *dev)
        struct panfrost_device *pfdev = dev_get_drvdata(dev);
        int ret;
 
+       if (pfdev->comp->pm_features & BIT(GPU_PM_VREG_OFF)) {
+               unsigned long freq = pfdev->pfdevfreq.fast_rate;
+               struct dev_pm_opp *opp;
+
+               opp = dev_pm_opp_find_freq_ceil(dev, &freq);
+               if (IS_ERR(opp))
+                       return PTR_ERR(opp);
+               dev_pm_opp_put(opp);
+               dev_pm_opp_set_opp(dev, opp);
+       }
+
        if (pfdev->comp->pm_features & BIT(GPU_PM_CLK_DIS)) {
                ret = clk_enable(pfdev->clock);
                if (ret)
-                       return ret;
+                       goto err_clk;
 
                if (pfdev->bus_clock) {
                        ret = clk_enable(pfdev->bus_clock);
@@ -455,6 +466,9 @@ static int panfrost_device_resume(struct device *dev)
 err_bus_clk:
        if (pfdev->comp->pm_features & BIT(GPU_PM_CLK_DIS))
                clk_disable(pfdev->clock);
+err_clk:
+       if (pfdev->comp->pm_features & BIT(GPU_PM_VREG_OFF))
+               dev_pm_opp_set_opp(dev, NULL);
        return ret;
 }
 
@@ -474,6 +488,9 @@ static int panfrost_device_suspend(struct device *dev)
                        clk_disable(pfdev->bus_clock);
        }
 
+       if (pfdev->comp->pm_features & BIT(GPU_PM_VREG_OFF))
+               dev_pm_opp_set_opp(dev, NULL);
+
        return 0;
 }
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h 
b/drivers/gpu/drm/panfrost/panfrost_device.h
index d7f179eb8ea3..0fc558db6bfd 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -28,9 +28,11 @@ struct panfrost_perfcnt;
 /**
  * enum panfrost_gpu_pm - Supported kernel power management features
  * @GPU_PM_CLK_DIS:  Allow disabling clocks during system suspend
+ * @GPU_PM_VREG_OFF: Allow turning off regulators during system suspend
  */
 enum panfrost_gpu_pm {
        GPU_PM_CLK_DIS,
+       GPU_PM_VREG_OFF,
 };
 
 struct panfrost_features {
-- 
2.42.0