linux-kernel - [PATCH v4 4/5] drm/panfrost: devfreq: set opp to the recommended one to configure regulator

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Date:   Tue,  6 Sep 2022 17:30:33 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Clément Péron <peron.clem@...il.com>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH v4 4/5] drm/panfrost: devfreq: set opp to the recommended one to configure regulator

Enabling panfrost GPU OPP with dynamic regulator will make OPP
responsible to enable and configure it.

Unfortunatly OPP configure and enable the regulator when an OPP
is asked to be set, which is not the case during
panfrost_devfreq_init().

This leave the regulator unconfigured and if no GPU load is
triggered, no OPP is asked to be set which make the regulator framework
switching it off during regulator_late_cleanup() without
noticing and therefore make the board hang as any access to GPU
memory space make bus locks up.

Call dev_pm_opp_set_opp() with the recommend OPP in
panfrost_devfreq_init() to enable the regulator, this will properly
configure and enable the regulator and will avoid any switch off
by regulator_late_cleanup().

Suggested-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Clément Péron <peron.clem@...il.com>
---
 drivers/gpu/drm/panfrost/panfrost_devfreq.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
index 5110cd9b2425..fe5f12f16a63 100644
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
@@ -131,6 +131,17 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
 		return PTR_ERR(opp);
 
 	panfrost_devfreq_profile.initial_freq = cur_freq;
+
+	/*
+	 * Set the recommend OPP this will enable and configure the regulator
+	 * if any and will avoid a switch off by regulator_late_cleanup()
+	 */
+	ret = dev_pm_opp_set_opp(dev, opp);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "Couldn't set recommended OPP\n");
+		return ret;
+	}
+
 	dev_pm_opp_put(opp);
 
 	/*
-- 
2.34.1