On Wed May 20 17:30:22 2026 +0530, Jai Luthra wrote:
> 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
> the suspend notifier might complete before the userspace has completed
> all ioctls, like QBUF/DQBUF/STREAMON/STREAMOFF.
>
> Tested-by: Rishikesh Donadkar <[email protected]>
> Reviewed-by: Rishikesh Donadkar <[email protected]>
> Signed-off-by: Jai Luthra <[email protected]>
> Signed-off-by: Rishikesh Donadkar <[email protected]>
> Reviewed-by: Tomi Valkeinen <[email protected]>
> Signed-off-by: Sakari Ailus <[email protected]>
Patch committed.
Thanks,
Sakari Ailus
.../media/platform/ti/j721e-csi2rx/j721e-csi2rx.c | 135 +++++++++++++++++++++
1 file changed, 135 insertions(+)
---
diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
index d68b8d6ffeb1..21388284cbaa 100644
--- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
+++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
@@ -131,6 +131,7 @@ struct ti_csi2rx_dev {
struct v4l2_subdev *source;
struct v4l2_subdev subdev;
struct ti_csi2rx_ctx ctx[TI_CSI2RX_MAX_CTX];
+ struct notifier_block pm_notifier;
u8 pix_per_clk;
/* Buffer to drain stale data from PSI-L endpoint */
struct {
@@ -1544,6 +1545,124 @@ static int ti_csi2rx_runtime_resume(struct device *dev)
return 0;
}
+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_ctx *ctx;
+ struct ti_csi2rx_dma *dma;
+ unsigned long flags = 0;
+ int i, ret = 0;
+
+ /* If device was not in use we can simply suspend */
+ if (pm_runtime_status_suspended(dev))
+ return 0;
+
+ /*
+ * If device is running, assert the pixel reset to cleanly stop any
+ * on-going streams before we suspend.
+ */
+ writel(0, csi->shim + SHIM_CNTL);
+
+ for (i = 0; i < csi->num_ctx; i++) {
+ ctx = &csi->ctx[i];
+ dma = &ctx->dma;
+
+ 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_disable_streams(&csi->subdev,
+
TI_CSI2RX_PAD_FIRST_SOURCE + ctx->idx,
+ BIT(0));
+ if (ret)
+ dev_err(csi->dev, "Failed to stop subdev
stream\n");
+ }
+
+ /* Stop any on-going streams */
+ writel(0, csi->shim + SHIM_DMACNTX(ctx->idx));
+
+ /* Drain DMA */
+ ti_csi2rx_drain_dma(ctx);
+
+ /* Terminate DMA */
+ ret = dmaengine_terminate_sync(ctx->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_ctx *ctx;
+ struct ti_csi2rx_dma *dma;
+ struct ti_csi2rx_buffer *buf;
+ unsigned long flags = 0;
+ unsigned int reg;
+ int i, ret = 0;
+
+ /* If device was not in use, we can simply wakeup */
+ if (pm_runtime_status_suspended(dev))
+ return 0;
+
+ /* If device was in use before, restore all the running streams */
+ reg = SHIM_CNTL_PIX_RST;
+ writel(reg, csi->shim + SHIM_CNTL);
+
+ for (i = 0; i < csi->num_ctx; i++) {
+ ctx = &csi->ctx[i];
+ dma = &ctx->dma;
+ 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, &ctx->dma.submitted, list) {
+ ti_csi2rx_start_dma(ctx, buf);
+ }
+ spin_unlock_irqrestore(&dma->lock, flags);
+
+ /* Restore stream config */
+ ti_csi2rx_setup_shim(ctx);
+
+ ret = v4l2_subdev_enable_streams(&csi->subdev,
+
TI_CSI2RX_PAD_FIRST_SOURCE + ctx->idx,
+ BIT(0));
+ if (ret)
+ dev_err(ctx->csi->dev, "Failed to start
subdev\n");
+ } else {
+ spin_unlock_irqrestore(&dma->lock, flags);
+ }
+ }
+
+ 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)
@@ -1617,6 +1736,20 @@ static int ti_csi2rx_probe(struct platform_device *pdev)
goto err_notifier;
}
+ /*
+ * Use PM notifier instead of .suspend/.resume callbacks because the
+ * ordering of callbacks among camera pipeline devices (sensor, serdes,
+ * CSI bridge) cannot be enforced even with device links. The notifier
+ * is called when the system is fully functional, ensuring all
+ * dependencies are available when stopping/starting streams.
+ */
+ 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_notifier;
+ }
+
return 0;
err_notifier:
@@ -1644,6 +1777,8 @@ static void ti_csi2rx_remove(struct platform_device *pdev)
ti_csi2rx_cleanup_ctx(&csi->ctx[i]);
ti_csi2rx_cleanup_notifier(csi);
+ unregister_pm_notifier(&csi->pm_notifier);
+
ti_csi2rx_cleanup_v4l2(csi);
dma_free_coherent(csi->dev, csi->drain.len, csi->drain.vaddr,
csi->drain.paddr);
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