FAILED: patch "[PATCH] pmdomain: bcm: bcm2835-power: Increase ASB control timeout" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x b826d2c0b0ecb844c84431ba6b502e744f5d919a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026032026-divisive-wieldable-7957@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From b826d2c0b0ecb844c84431ba6b502e744f5d919a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ADra=20Canal?= <[email protected]>
Date: Tue, 17 Mar 2026 19:41:49 -0300
Subject: [PATCH] pmdomain: bcm: bcm2835-power: Increase ASB control timeout
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The bcm2835_asb_control() function uses a tight polling loop to wait for the ASB bridge to acknowledge a request. During intensive workloads, this handshake intermittently fails for V3D's master ASB on BCM2711, resulting in "Failed to disable ASB master for v3d" errors during runtime PM suspend. As a consequence, the failed power-off leaves V3D in a broken state, leading to bus faults or system hangs on later accesses.

As the timeout is insufficient in some scenarios, increase the polling timeout from 1us to 5us, which is still negligible in the context of a power domain transition. Also, replace the open-coded ktime_get_ns()/ cpu_relax() polling loop with readl_poll_timeout_atomic().

index 0450202bbee2..eee87a300532 100644
@@ -9,6 +9,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/mfd/bcm2835-pm.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>

@@ -153,7 +154,6 @@ struct bcm2835_power {
 static int bcm2835_asb_control(struct bcm2835_power *power, u32 reg, bool enable)
 {
 	void __iomem *base = power->asb;
-	u64 start;
 	u32 val;
 
 	switch (reg) {

@@ -166,8 +166,6 @@ static int bcm2835_asb_control(struct bcm2835_power *power, u32 reg, bool enable
 		break;
 	}
 
-	start = ktime_get_ns();
-
 	/* Enable the module's async AXI bridges. */
 	if (enable) {
 		val = readl(base + reg) & ~ASB_REQ_STOP;

@@ -176,11 +174,9 @@ static int bcm2835_asb_control(struct bcm2835_power *power, u32 reg, bool enable
 	}
 	writel(PM_PASSWORD | val, base + reg);
 
-	while (!!(readl(base + reg) & ASB_ACK) == enable) {
-		cpu_relax();
-		if (ktime_get_ns() - start >= 1000)
-			return -ETIMEDOUT;
-	}
+	if (readl_poll_timeout_atomic(base + reg, val,
+				      !!(val & ASB_ACK) != enable, 0, 5))
+		return -ETIMEDOUT;
 
 	return 0;
 }

From: Maíra Canal <[email protected]>

[ Upstream commit b826d2c0b0ecb844c84431ba6b502e744f5d919a ]

The bcm2835_asb_control() function uses a tight polling loop to wait for the ASB bridge to acknowledge a request. During intensive workloads, this handshake intermittently fails for V3D's master ASB on BCM2711, resulting in "Failed to disable ASB master for v3d" errors during runtime PM suspend. As a consequence, the failed power-off leaves V3D in a broken state, leading to bus faults or system hangs on later accesses.

As the timeout is insufficient in some scenarios, increase the polling timeout from 1us to 5us, which is still negligible in the context of a power domain transition. Also, replace the open-coded ktime_get_ns()/ cpu_relax() polling loop with readl_poll_timeout_atomic().

---
 drivers/soc/bcm/bcm2835-power.c | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

index 1e0041ec81323..6a82c66c6674a 100644
@@ -9,6 +9,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/mfd/bcm2835-pm.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>

@@ -150,40 +151,34 @@ struct bcm2835_power {
 
 static int bcm2835_asb_enable(struct bcm2835_power *power, u32 reg)
 {
-	u64 start;
+	u32 val;
 
 	if (!reg)
 		return 0;
 
-	start = ktime_get_ns();
-
 	/* Enable the module's async AXI bridges. */
 	ASB_WRITE(reg, ASB_READ(reg) & ~ASB_REQ_STOP);
-	while (ASB_READ(reg) & ASB_ACK) {
-		cpu_relax();
-		if (ktime_get_ns() - start >= 1000)
-			return -ETIMEDOUT;
-	}
+
+	if (readl_poll_timeout_atomic(power->asb + reg, val,
+				      !(val & ASB_ACK), 0, 5))
+		return -ETIMEDOUT;
 
 	return 0;
 }
 
 static int bcm2835_asb_disable(struct bcm2835_power *power, u32 reg)
 {
-	u64 start;
+	u32 val;
 
 	if (!reg)
 		return 0;
 
-	start = ktime_get_ns();
-
 	/* Enable the module's async AXI bridges. */
 	ASB_WRITE(reg, ASB_READ(reg) | ASB_REQ_STOP);
-	while (!(ASB_READ(reg) & ASB_ACK)) {
-		cpu_relax();
-		if (ktime_get_ns() - start >= 1000)
-			return -ETIMEDOUT;
-	}
+
+	if (readl_poll_timeout_atomic(power->asb + reg, val,
+				      !!(val & ASB_ACK), 0, 5))
+		return -ETIMEDOUT;
 
 	return 0;
 }

2.51.0