kernel-agent/patches/driver/bes2600/pm-gate-on-handshake/0001-bes2600-gate-device-LP-mode-entry-on-successful-handshake.patch

From 19feb8181a75caa13442f5ac436b4014e68fe416 Mon Sep 17 00:00:00 2001
From: Markus Fritsche <fritsche.markus@gmail.com>
Date: Wed, 22 Apr 2026 12:37:45 +0200
Subject: [PATCH 04/29] bes2600: gate device LP-mode entry on successful
 per-VIF firmware handshake

bes2600_pwr_enter_lp_mode() drives the transition to low-power for each
associated STA VIF: it pushes wsm_set_pm(), waits up to 5 seconds on
pm_enter_cmpl for the firmware to acknowledge, then unconditionally
calls bes2600_pwr_device_enter_lp_mode() to drop the device end of the
bus.

Two bugs:

1. A failed wsm_set_pm() only logs an error, then still falls into
   wait_for_completion_timeout() on a completion the firmware will
   never post (the set-mode command never reached it). The loop
   therefore always blocks the full 5 s, logs a second error, and
   proceeds.

2. A genuine wait-timeout (firmware received the set-mode command but
   never posted the indication) also only logs a warning. The code
   then drops to bes2600_pwr_device_enter_lp_mode(), handing the
   device subsystem an inconsistent view of mac-layer state.

On PineTab2 (BES2600WM + RK3566) the second bug is the recurring
root-cause of the 'bes2600_pwr_enter_lp_mode, wait pm ind timeout'
message flooding dmesg every 5-10 s when the interface is associated
and idle. Sending the device to LP in that state cascades into the
SDIO TX path as the 'bes_sdio_memcpy_to_io_helper / sdio_tx_work'
WARN splat.

Fix:
  - Add a 'timeouts' counter; bump it on both failure paths.
  - Skip the wait_for_completion entirely when wsm_set_pm() failed
    (there is no completion to wait for).
  - Only call bes2600_pwr_device_enter_lp_mode() when every per-VIF
    handshake reached firmware-ACKed completion; otherwise return
    -ETIMEDOUT and leave the device in its current power state.

Tested-on: PineTab2 running linux-pinetab2 6.19.10-danctnix1-1.
Post-patch the handshake still fails on this particular firmware
revision (separate root-cause investigation outside this patch), but
the driver now returns -ETIMEDOUT cleanly instead of flooding dmesg
and destabilising the SDIO path.

Signed-off-by: Markus Fritsche <fritsche.markus@gmail.com>
---
 bes2600/bes_pwr.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/bes2600/bes_pwr.c b/drivers/staging/bes2600/bes_pwr.c
index e7a1045..f62ae22 100644
--- a/drivers/staging/bes2600/bes_pwr.c
+++ b/drivers/staging/bes2600/bes_pwr.c
@@ -472,6 +472,7 @@ static int bes2600_pwr_enter_lp_mode(struct bes2600_common *hw_priv)
 	int i = 0;
 	struct bes2600_vif *priv;
 	int ret = 0;
+	int timeouts = 0;
 	char ip_str[20];
 	unsigned long status = 0;
 
@@ -528,22 +529,35 @@ static int bes2600_pwr_enter_lp_mode(struct bes2600_common *hw_priv)
 				if (ret) {
 					atomic_set(&hw_priv->bes_power.pm_set_in_process, 0);
 					bes_err("%s, set operation mode fail\n", __func__);
+					timeouts++;
+					continue;
 				}
 
 				/* wait power save mode changed indication */
 				status = wait_for_completion_timeout(&hw_priv->bes_power.pm_enter_cmpl, 5 * HZ);
 				atomic_set(&hw_priv->bes_power.pm_set_in_process, 0);
 				reinit_completion(&hw_priv->bes_power.pm_enter_cmpl);
-				if (!status)
+				if (!status) {
 					bes_err("%s, wait pm ind timeout\n", __func__);
+					timeouts++;
+				}
 			} else {
 				bes_devel("skip enter lp mode\n");
 			}
 		}
 	}
 
-	/* set device low power configuration */
-	bes2600_pwr_device_enter_lp_mode(hw_priv);
+	/*
+	 * Enter the device-end of the LP transition only if every per-VIF
+	 * mac80211 handshake reached firmware-ACKed completion. Doing the
+	 * device-LP setup while any VIF is still pending leaves the driver
+	 * in an inconsistent state that cascades into SDIO TX errors on
+	 * the BES2600.
+	 */
+	if (timeouts == 0)
+		bes2600_pwr_device_enter_lp_mode(hw_priv);
+	else
+		ret = -ETIMEDOUT;
 
 	return ret;
 }
-- 
2.54.0