Hi Stefan,

On 18/03/26 08:51, Stefan Wahren wrote:

Hi Maíra,

Am 17.03.26 um 23:41 schrieb Maíra Canal:

quoted

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().

personally I would have moved all readl_poll_timeout_atomic changes in 
the second patch, to avoid possible conflicts in stable. But no strong 
opinion about this.

TBH personally, I also agree. But, as I don't have a strong opinion
about it, I prioritized addressing Ulf's feedback in the last version
[1].

[1] 
https://lore.kernel.org/dri-devel/20260312-v3d-power-management-v7-0-9f006a1d4c55@igalia.com/T/#mf96146960ec7ffeea32e732c95ccf9548af21748 (local)

Best regards,
- Maíra

Best regards

quoted

Cc: stable@vger.kernel.org
Fixes: 670c672608a1 ("soc: bcm: bcm2835-pm: Add support for power 
domains under a new binding.")
Signed-off-by: Maíra Canal <mcanal@igalia.com>
---
  drivers/pmdomain/bcm/bcm2835-power.c | 12 ++++--------
  1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/pmdomain/bcm/bcm2835-power.c b/drivers/pmdomain/ 

bcm/bcm2835-power.c
index 
0450202bbee2513c9116a36abaa839b460550935..eee87a3005325848547ce1f5fd729b168a641460 100644

--- a/drivers/pmdomain/bcm/bcm2835-power.c
+++ b/drivers/pmdomain/bcm/bcm2835-power.c

@@ -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;
  }