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Message-Id: <20250224-ti_csi_pm-v1-3-8f8c29ef646d@ideasonboard.com>
Date: Mon, 24 Feb 2025 19:05:58 +0530
From: Jai Luthra <jai.luthra@...asonboard.com>
To: Mauro Carvalho Chehab <mchehab@...nel.org>,
Maxime Ripard <mripard@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>,
Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
Changhuang Liang <changhuang.liang@...rfivetech.com>,
Devarsh Thakkar <devarsht@...com>, Jai Luthra <jai.luthra@...asonboard.com>
Subject: [PATCH 3/3] media: ti: j721e-csi2rx: Support system suspend using
pm_notifier
As this device is the "orchestrator" for the rest of the media
pipeline, we need to stop all on-going streams before system suspend and
enable them back when the system wakes up from sleep.
Using .suspend/.resume callbacks does not work, as the order of those
callbacks amongst various devices in the camera pipeline like the sensor,
FPD serdes, CSI bridge etc. is impossible to enforce, even with
device links. For example, the Cadence CSI bridge is a child device of
this device, thus we cannot create a device link with the CSI bridge as
a provider and this device as consumer. This can lead to situations
where all the dependencies for the bridge have not yet resumed when we
request the subdev to start streaming again through the .resume callback
defined in this device.
Instead here we register a notifier callback with the PM framework
which is triggered when the system is fully functional. At this point we
can cleanly stop or start the streams, because we know all other devices
and their dependencies are functional. A downside of this approach is
that the userspace is also alive (not frozen yet, or just thawed), so to
prevent races from userspace ioctl calls we hold the lock for the video
device operations while we are dealing with the notifier events.
Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
---
.../media/platform/ti/j721e-csi2rx/j721e-csi2rx.c | 109 +++++++++++++++++++++
1 file changed, 109 insertions(+)
diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
index dc15759562f94fcfc53955b455b7e03fb733e8e4..5a318b2080532882b0f0fcbde8e1c35208d198c7 100644
--- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
+++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
@@ -107,6 +107,7 @@ struct ti_csi2rx_dev {
struct mutex mutex; /* To serialize ioctls. */
struct v4l2_format v_fmt;
struct ti_csi2rx_dma dma;
+ struct notifier_block pm_notifier;
u32 sequence;
};
@@ -1121,6 +1122,105 @@ static int ti_csi2rx_runtime_resume(struct device *dev)
return ti_csi2rx_dma_request_chan(csi);
}
+static int ti_csi2rx_suspend(struct device *dev)
+{
+ struct ti_csi2rx_dev *csi = dev_get_drvdata(dev);
+ enum ti_csi2rx_dma_state state;
+ struct ti_csi2rx_dma *dma = &csi->dma;
+ unsigned long flags = 0;
+ int ret = 0;
+
+ /* If device was not in use we can simply suspend */
+ if (pm_runtime_status_suspended(dev))
+ return 0;
+
+ /* Acquire the lock used for video dev/queue operations */
+ mutex_lock(&csi->mutex);
+
+ /* Stop any on-going streams */
+ writel(0, csi->shim + SHIM_CNTL);
+ writel(0, csi->shim + SHIM_DMACNTX);
+
+ spin_lock_irqsave(&dma->lock, flags);
+ state = dma->state;
+ spin_unlock_irqrestore(&dma->lock, flags);
+
+ if (state != TI_CSI2RX_DMA_STOPPED) {
+ /* Disable source */
+ ret = v4l2_subdev_call(csi->source, video, s_stream, 0);
+ if (ret)
+ dev_err(csi->dev, "Failed to stop subdev stream\n");
+ }
+
+ /* Drain DMA */
+ ti_csi2rx_drain_dma(csi);
+
+ /* Terminate DMA */
+ ret = dmaengine_terminate_sync(csi->dma.chan);
+ if (ret)
+ dev_err(csi->dev, "Failed to stop DMA\n");
+
+ return ret;
+}
+
+static int ti_csi2rx_resume(struct device *dev)
+{
+ struct ti_csi2rx_dev *csi = dev_get_drvdata(dev);
+ struct ti_csi2rx_dma *dma = &csi->dma;
+ struct ti_csi2rx_buffer *buf;
+ unsigned long flags = 0;
+ int ret = 0;
+
+ /* If device was not in use, we can simply wakeup */
+ if (pm_runtime_status_suspended(dev))
+ return 0;
+
+ spin_lock_irqsave(&dma->lock, flags);
+ if (dma->state != TI_CSI2RX_DMA_STOPPED) {
+ /* Re-submit all previously submitted buffers to DMA */
+ list_for_each_entry(buf, &csi->dma.submitted, list) {
+ ti_csi2rx_start_dma(csi, buf);
+ }
+ spin_unlock_irqrestore(&dma->lock, flags);
+
+ /* Restore stream config */
+ ti_csi2rx_setup_shim(csi);
+
+ ret = v4l2_subdev_call(csi->source, video, s_stream, 1);
+ if (ret)
+ dev_err(csi->dev, "Failed to start subdev\n");
+ } else {
+ spin_unlock_irqrestore(&dma->lock, flags);
+ }
+
+ /* Release the lock used for video dev/queue operations */
+ mutex_unlock(&csi->mutex);
+
+ return ret;
+}
+
+static int ti_csi2rx_pm_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct ti_csi2rx_dev *csi =
+ container_of(nb, struct ti_csi2rx_dev, pm_notifier);
+
+ switch (action) {
+ case PM_HIBERNATION_PREPARE:
+ case PM_SUSPEND_PREPARE:
+ case PM_RESTORE_PREPARE:
+ ti_csi2rx_suspend(csi->dev);
+ break;
+ case PM_POST_SUSPEND:
+ case PM_POST_HIBERNATION:
+ case PM_POST_RESTORE:
+ ti_csi2rx_resume(csi->dev);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
static const struct dev_pm_ops ti_csi2rx_pm_ops = {
RUNTIME_PM_OPS(ti_csi2rx_runtime_suspend, ti_csi2rx_runtime_resume,
NULL)
@@ -1167,6 +1267,13 @@ static int ti_csi2rx_probe(struct platform_device *pdev)
goto err_subdev;
}
+ csi->pm_notifier.notifier_call = ti_csi2rx_pm_notifier;
+ ret = register_pm_notifier(&csi->pm_notifier);
+ if (ret) {
+ dev_err(csi->dev, "Failed to create PM notifier: %d\n", ret);
+ goto err_subdev;
+ }
+
pm_runtime_set_active(csi->dev);
pm_runtime_enable(csi->dev);
pm_request_idle(csi->dev);
@@ -1192,6 +1299,8 @@ static void ti_csi2rx_remove(struct platform_device *pdev)
video_unregister_device(&csi->vdev);
+ unregister_pm_notifier(&csi->pm_notifier);
+
ti_csi2rx_cleanup_vb2q(csi);
ti_csi2rx_cleanup_subdev(csi);
ti_csi2rx_cleanup_v4l2(csi);
--
2.48.1
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