linux-kernel - [PATCH 2/3] drm/panthor: Retry OPP transition to suspension state a few times

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Message-ID: <20241011225906.3789965-2-adrian.larumbe@collabora.com>
Date: Fri, 11 Oct 2024 23:57:00 +0100
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Boris Brezillon <boris.brezillon@...labora.com>,
	Steven Price <steven.price@....com>,
	Liviu Dudau <liviu.dudau@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Cc: kernel@...labora.com,
	Adrián Larumbe <adrian.larumbe@...labora.com>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] drm/panthor: Retry OPP transition to suspension state a few times

When the device's runtime PM suspend callback is invoked, the switch to
a suspension OPP might sometimes fail. Although this is beyond the
control of the Panthor driver, we can attempt suspending it more than
once as a defensive strategy.

Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>
---
 drivers/gpu/drm/panthor/panthor_device.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index cedd3cbcb47d..5430557bd0b8 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -490,6 +490,7 @@ int panthor_device_resume(struct device *dev)
 int panthor_device_suspend(struct device *dev)
 {
 	struct panthor_device *ptdev = dev_get_drvdata(dev);
+	unsigned int susp_retries;
 	int ret, cookie;
 
 	if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE)
@@ -522,7 +523,12 @@ int panthor_device_suspend(struct device *dev)
 		drm_dev_exit(cookie);
 	}
 
-	ret = panthor_devfreq_suspend(ptdev);
+	for (susp_retries = 0; susp_retries < 5; susp_retries++) {
+		ret = panthor_devfreq_suspend(ptdev);
+		if (!ret)
+			break;
+	}
+
 	if (ret) {
 		if (panthor_device_is_initialized(ptdev) &&
 		    drm_dev_enter(&ptdev->base, &cookie)) {
-- 
2.46.2