FAILED: patch "[PATCH] spi: spi-zynqmp-gqspi: stop the controller on shutdown" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x e922bad8b2d5028c51a096d083fea41cd0987154
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092228-clasp-turmoil-85b0@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e922bad8b2d5028c51a096d083fea41cd0987154 Mon Sep 17 00:00:00 2001
From: Itai Handler <[email protected]>
Date: Thu, 10 Sep 2026 20:48:32 +0300
Subject: [PATCH] spi: spi-zynqmp-gqspi: stop the controller on shutdown

The driver has no ->shutdown, and platform_drv_shutdown() has no fallback of its own. Unlike pci_device_shutdown(), which clears bus mastering when kexec_in_progress, nothing on the platform bus disarms a device that can still write to memory. The normal kexec path never calls ->suspend either, so the quiesce in zynqmp_qspi_suspend() is not reached.

A controller that is still executing a DMA read may therefore keep writing to memory across a kexec. QSPIDMA_DST_ADDR still points at memory owned by the kernel that called kexec, DST_SIZE is non-zero and the flash is still clocked, so data can keep landing in RAM while the new kernel is being relocated, and after it has started executing.

That destination is a physical address which means nothing to the new kernel, so the writes can corrupt whatever now occupies it: kernel text or data, page tables, or the initrd. Nothing reports an error and the resulting behaviour is undefined.

This can be observed by reading GQSPI_EN (offset 0x114) and QSPIDMA_DST_ADDR/SIZE/STS/CTRL (offsets 0x800 to 0x80c) early in the new kernel, before the driver probes: without this patch GQSPI_EN reads 1 and QSPIDMA_DST_ADDR still points into the previous kernel's memory.

Add a ->shutdown that stops the controller the way zynqmp_qspi_suspend() already does. spi_controller_suspend() stops the queue, waits for a message that is already executing and makes any later transfer fail with -ESHUTDOWN, so nothing can be cut short by the register write that follows. It may sleep, which is fine here: device_shutdown() runs in process context. Unlike ->suspend this cannot abort on error, because a controller left mastering the bus is worse than a truncated transfer, so a failure to drain is only logged.

GQSPI_EN_OFST is then cleared, as zynqmp_qspi_remove() and zynqmp_qspi_suspend() already do. Skip that write only when pm_runtime_get_if_in_use() returns 0, i.e. runtime suspended: the clocks are gated, so the registers are unreachable and the controller cannot be mastering the bus. A negative return is not the same thing - it is what the CONFIG_PM=n stub always returns, and there probe() has enabled pclk and refclk for good, so the controller is running and must be stopped.

index 4d55090fa443..15e9d3ef8839 100644
@@ -1373,11 +1373,45 @@ static void zynqmp_qspi_remove(struct platform_device *pdev)
 	clk_disable_unprepare(xqspi->pclk);
 }
 
+static void zynqmp_qspi_shutdown(struct platform_device *pdev)
+{
+	struct zynqmp_qspi *xqspi = platform_get_drvdata(pdev);
+	int ret;
+
+	/*
+	 * Stop the queue and reject any later transfer first, so the write
+	 * below cannot cut into a message that is still being executed.
+	 * Unlike ->suspend this cannot abort on error: a controller left
+	 * mastering the bus is worse than a truncated transfer.
+	 */
+	ret = spi_controller_suspend(xqspi->ctlr);
+	if (ret)
+		dev_warn(&pdev->dev, "could not stop the queue: %d\n", ret);
+
+	/*
+	 * Only a runtime suspended controller can be left alone: its clocks
+	 * are gated, so it cannot be mastering the bus, and its registers
+	 * must not be accessed either.  Any other answer means it may be
+	 * running and has to be stopped.  In particular, on a kernel built
+	 * without runtime PM this returns -EINVAL, and there the clocks
+	 * enabled in probe() are never gated at all.
+	 */
+	ret = pm_runtime_get_if_in_use(&pdev->dev);
+	if (!ret)
+		return;
+
+	zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, 0x0);
+
+	if (ret > 0)
+		pm_runtime_put_noidle(&pdev->dev);
+}
+
 MODULE_DEVICE_TABLE(of, zynqmp_qspi_of_match);
 
 static struct platform_driver zynqmp_qspi_driver = {
 	.probe = zynqmp_qspi_probe,
 	.remove = zynqmp_qspi_remove,
+	.shutdown = zynqmp_qspi_shutdown,
 	.driver = {
 		.name = "zynqmp-qspi",
 		.of_match_table = zynqmp_qspi_of_match,

commit e922bad8b2d5028c51a096d083fea41cd0987154 upstream.

The driver has no ->shutdown, and platform_drv_shutdown() has no fallback of its own. Unlike pci_device_shutdown(), which clears bus mastering when kexec_in_progress, nothing on the platform bus disarms a device that can still write to memory. The normal kexec path never calls ->suspend either, so the quiesce in zynqmp_qspi_suspend() is not reached.

A controller that is still executing a DMA read may therefore keep writing to memory across a kexec. QSPIDMA_DST_ADDR still points at memory owned by the kernel that called kexec, DST_SIZE is non-zero and the flash is still clocked, so data can keep landing in RAM while the new kernel is being relocated, and after it has started executing.

That destination is a physical address which means nothing to the new kernel, so the writes can corrupt whatever now occupies it: kernel text or data, page tables, or the initrd. Nothing reports an error and the resulting behaviour is undefined.

This can be observed by reading GQSPI_EN (offset 0x114) and QSPIDMA_DST_ADDR/SIZE/STS/CTRL (offsets 0x800 to 0x80c) early in the new kernel, before the driver probes: without this patch GQSPI_EN reads 1 and QSPIDMA_DST_ADDR still points into the previous kernel's memory.

Add a ->shutdown that stops the controller the way zynqmp_qspi_suspend() already does. spi_controller_suspend() stops the queue, waits for a message that is already executing and makes any later transfer fail with -ESHUTDOWN, so nothing can be cut short by the register write that follows. It may sleep, which is fine here: device_shutdown() runs in process context. Unlike ->suspend this cannot abort on error, because a controller left mastering the bus is worse than a truncated transfer, so a failure to drain is only logged.

GQSPI_EN_OFST is then cleared, as zynqmp_qspi_remove() and zynqmp_qspi_suspend() already do. Skip that write only when pm_runtime_get_if_in_use() returns 0, i.e. runtime suspended: the clocks are gated, so the registers are unreachable and the controller cannot be mastering the bus. A negative return is not the same thing - it is what the CONFIG_PM=n stub always returns, and there probe() has enabled pclk and refclk for good, so the controller is running and must be stopped.

[ itai: context only - zynqmp_qspi_of_match[] still sits between
zynqmp_qspi_remove() and MODULE_DEVICE_TABLE() in this tree, hoisted to the top of the file upstream by commit 29f4d95b97bc ("spi:
spi-zynqmp-gqspi: Add tap delay support for GQSPI controller on Versal platform"), so zynqmp_qspi_shutdown() is placed above it ]

---
 drivers/spi/spi-zynqmp-gqspi.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

index bbc918815634..13f3abef4349 100644
@@ -1220,6 +1220,39 @@ static int zynqmp_qspi_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void zynqmp_qspi_shutdown(struct platform_device *pdev)
+{
+	struct zynqmp_qspi *xqspi = platform_get_drvdata(pdev);
+	int ret;
+
+	/*
+	 * Stop the queue and reject any later transfer first, so the write
+	 * below cannot cut into a message that is still being executed.
+	 * Unlike ->suspend this cannot abort on error: a controller left
+	 * mastering the bus is worse than a truncated transfer.
+	 */
+	ret = spi_controller_suspend(xqspi->ctlr);
+	if (ret)
+		dev_warn(&pdev->dev, "could not stop the queue: %d\n", ret);
+
+	/*
+	 * Only a runtime suspended controller can be left alone: its clocks
+	 * are gated, so it cannot be mastering the bus, and its registers
+	 * must not be accessed either.  Any other answer means it may be
+	 * running and has to be stopped.  In particular, on a kernel built
+	 * without runtime PM this returns -EINVAL, and there the clocks
+	 * enabled in probe() are never gated at all.
+	 */
+	ret = pm_runtime_get_if_in_use(&pdev->dev);
+	if (!ret)
+		return;
+
+	zynqmp_gqspi_write(xqspi, GQSPI_EN_OFST, 0x0);
+
+	if (ret > 0)
+		pm_runtime_put_noidle(&pdev->dev);
+}
+
 static const struct of_device_id zynqmp_qspi_of_match[] = {
 	{ .compatible = "xlnx,zynqmp-qspi-1.0", },
 	{ /* End of table */ }

@@ -1230,6 +1263,7 @@ MODULE_DEVICE_TABLE(of, zynqmp_qspi_of_match);
 static struct platform_driver zynqmp_qspi_driver = {
 	.probe = zynqmp_qspi_probe,
 	.remove = zynqmp_qspi_remove,
+	.shutdown = zynqmp_qspi_shutdown,
 	.driver = {
 		.name = "zynqmp-qspi",
 		.of_match_table = zynqmp_qspi_of_match,

2.34.1

Thanks for looking into this.

I agree with your analysis of the 5.10 runtime-PM state: because of the probe-time runtime-PM imbalance, pm_runtime_get_if_in_use() cannot be used reliably in this path on 5.10.

However, I don't think we should change the backport to unconditionally write GQSPI_EN. The upstream patch intentionally avoids accessing the GQSPI registers when the controller is runtime-suspended, since its clocks are then disabled.

I'd also prefer not to introduce different runtime-PM/MMIO logic in the 5.10 backport just to work around the 5.10-specific usage_count issue.

I suggest dropping this backport for now and first fixing the runtime-PM logic in the 5.10 tree. Once that is fixed, we can revisit the GQSPI shutdown patch and backport it with the same runtime-PM logic as upstream.

This also avoids potentially accessing the GQSPI register block while the controller is runtime-suspended.

If that sounds reasonable, let's drop the 5.10 backport for now.

Thanks,
Itai

Agreed. 5.10 stays without it for now.

Thanks,
Sasha