[PATCH v3 1/8] drm/panfrost: Rework runtime PM initialization

From: Rob Herring <robh@kernel.org>
To: dri-devel@lists.freedesktop.org
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>,
	David Airlie <airlied@linux.ie>,
	Steven Price <steven.price@arm.com>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH v3 1/8] drm/panfrost: Rework runtime PM initialization
Date: Mon, 26 Aug 2019 17:33:10 -0500	[thread overview]
Message-ID: <20190826223317.28509-2-robh@kernel.org> (raw)
In-Reply-To: <20190826223317.28509-1-robh@kernel.org>

There's a few issues with the runtime PM initialization.

The documentation states pm_runtime_set_active() should be called before
pm_runtime_enable(). The pm_runtime_put_autosuspend() could suspend the GPU
before panfrost_perfcnt_init() is called which touches the h/w. The
autosuspend delay keeps things from breaking. There's no need explicitly
power off the GPU only to wake back up with pm_runtime_get_sync(). Just
delaying pm_runtime_enable to the end of probe is sufficient.

Lets move all the runtime PM calls into the probe() function so they are
all in one place and are done after all initialization.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Steven Price <steven.price@arm.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
---
v3:
 - Move autosuspend setup after pm_runtime_enable as only autosuspend changes
   trigger suspend.
 - Fix autosuspend delay to 50ms instead of 0.

 drivers/gpu/drm/panfrost/panfrost_device.c |  9 ---------
 drivers/gpu/drm/panfrost/panfrost_drv.c    | 10 ++++++----
 2 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index 4da71bb56c20..73805210834e 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -5,7 +5,6 @@
 #include <linux/clk.h>
 #include <linux/reset.h>
 #include <linux/platform_device.h>
-#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>

 #include "panfrost_device.h"
@@ -166,14 +165,6 @@ int panfrost_device_init(struct panfrost_device *pfdev)
 	if (err)
 		goto err_out4;

-	/* runtime PM will wake us up later */
-	panfrost_gpu_power_off(pfdev);
-
-	pm_runtime_set_active(pfdev->dev);
-	pm_runtime_get_sync(pfdev->dev);
-	pm_runtime_mark_last_busy(pfdev->dev);
-	pm_runtime_put_autosuspend(pfdev->dev);
-
 	err = panfrost_perfcnt_init(pfdev);
 	if (err)
 		goto err_out5;
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index d74442d71048..bc2ddeb55f5d 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -523,10 +523,6 @@ static int panfrost_probe(struct platform_device *pdev)
 	mutex_init(&pfdev->shrinker_lock);
 	INIT_LIST_HEAD(&pfdev->shrinker_list);

-	pm_runtime_use_autosuspend(pfdev->dev);
-	pm_runtime_set_autosuspend_delay(pfdev->dev, 50); /* ~3 frames */
-	pm_runtime_enable(pfdev->dev);
-
 	err = panfrost_device_init(pfdev);
 	if (err) {
 		if (err != -EPROBE_DEFER)
@@ -541,6 +537,12 @@ static int panfrost_probe(struct platform_device *pdev)
 		goto err_out1;
 	}

+	pm_runtime_set_active(pfdev->dev);
+	pm_runtime_mark_last_busy(pfdev->dev);
+	pm_runtime_enable(pfdev->dev);
+	pm_runtime_set_autosuspend_delay(pfdev->dev, 50); /* ~3 frames */
+	pm_runtime_use_autosuspend(pfdev->dev);
+
 	/*
 	 * Register the DRM device with the core and the connectors with
 	 * sysfs
--
2.20.1
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