bes2600: short-circuit wake handshake when chip is confirmed ACTIVE

The previous patch ("bes2600: gate PM indication completion on pending
request and track chip state") added enum bes2600_chip_pm_state and the
chip_pm_state field tracking what the host has *seen the firmware
confirm*. This patch makes the wake side use it.

Without this, every bes2600_pwr_device_exit_lp_mode() unconditionally
runs gpio_wake() + sbus_active() + wsm_set_operational_mode(active),
even when the chip is already in confirmed-ACTIVE state and the wake
sequence has nothing to do. The visible failure mode on PineTab2:

  bes2600_pwr_enter_lp_mode, wait pm ind timeout
  repeat set gpio_wake_flag, sub_sys:0
  bes2600_sdio_active failed, subsys:0
  bes2600_pwr_device_exit_lp_mode, active mcu fail

cycling every ~9 s, ~22 cycles in 10 minutes. Three pieces:

  1. enter_lp_mode timed out (firmware indication lost). With c6.1,
     chip_pm_state is now UNKNOWN.
  2. lock_device fires exit_lp_mode.
  3. gpio_wake hits "bit already set" because device_enter_lp_mode
     was skipped when the indication timed out, so gpio_sleep was
     never called - the bit reflects driver intent, not chip state.
     gpio_wake silently no-ops (no GPIO edge), bit stays set.
  4. sbus_active spends 200 x 2 ms looking for MCU_WAKEUP_READY that
     never comes (firmware was never told to wake), then fails.
  5. Driver continues to wsm_set_operational_mode against the wedged
     bus, compounding the failure.

This patch's three moves:

  * bes2600_pwr_device_exit_lp_mode() reads chip_pm_state at entry.
    On BES2600_CHIP_PM_ACTIVE, log at devel level and return without
    touching gpio_wake / sbus_active / WSM. The chip is in the state
    we want; the handshake exists only to drive a transition.

  * On BES2600_CHIP_PM_LP or BES2600_CHIP_PM_UNKNOWN, run the wake
    handshake as before, but on sbus_active() failure: set
    chip_pm_state = UNKNOWN, log once at err level, and bail out.
    Do NOT call wsm_set_operational_mode over a wedged bus - it
    would just emit a second error and leave the chip in an even
    less defined state.

  * bes2600_gpio_wakeup_mcu() / bes2600_gpio_allow_mcu_sleep():
    demote "repeat set/clear gpio_wake_flag" from bes_err to
    bes_devel. Multi-subsystem wake-hold (e.g. WIFI + BT both want
    MCU awake) is the steady-state case, and the symmetric clear
    while bit-already-clear is racy bookkeeping rather than a
    hardware error. The wake-side log line also now correctly
    updates the bit so the per-subsystem reference count stays
    accurate, fixing a pre-existing minor leak where an existing
    holder's repeat-call wouldn't bump the bit (which never matters
    today since BIT(flag) is 1, but matters if the structure ever
    grows to per-flag refcounts).

Net effect on the cycle:

  * If chip is genuinely ACTIVE (chip_pm_state == ACTIVE), wake skips
    cleanly. Storm goes silent.
  * If chip is genuinely LP, behaviour is unchanged.
  * If chip is UNKNOWN (post-timeout state), one wake attempt is
    made; on failure, state stays UNKNOWN and we don't emit a
    second cascade error per attempt. Repeated UNKNOWN with failed
    wake will eventually be picked up by the LMAC active-monitor
    and escalated to mmc_hw_reset (c5.2).

No new locks, no new state. Only consumption of the chip_pm_state
field added in the prerequisite patch.

Signed-off-by: Markus Fritsche <fritsche.markus@gmail.com>

bes2600/bes2600_sdio.c

@@ -1388,7 +1388,14 @@ static void bes2600_gpio_wakeup_mcu(struct sbus_priv *self, int flag)
 
 	/* error check */
 	if((self->gpio_wakup_flags & BIT(flag)) != 0) {
-		bes_err(			"repeat set gpio_wake_flag, sub_sys:%d", flag);
+		/*
+		 * Multiple subsystems holding wake is the steady-state case
+		 * (e.g. WIFI + BT both want MCU awake). Demoted from bes_err
+		 * to bes_devel since it isn't an error - the GPIO is already
+		 * asserted high and the subsystem is now also tracked.
+		 */
+		bes_devel("repeat set gpio_wake_flag, sub_sys:%d\n", flag);
+		self->gpio_wakup_flags |= BIT(flag);
 		mutex_unlock(&self->io_mutex);
 		return;
 	}
@@ -1420,7 +1427,11 @@ static void bes2600_gpio_allow_mcu_sleep(struct sbus_priv *self, int flag)
 
 	/* error check */
 	if((self->gpio_wakup_flags & BIT(flag)) == 0) {
-		bes_err(			"repeat clear gpio_wake_flag, sub_sys:%d", flag);
+		/*
+		 * Mirror of the wake path: a clear when the bit is already
+		 * clear is racy bookkeeping, not a hardware error.
+		 */
+		bes_devel("repeat clear gpio_wake_flag, sub_sys:%d\n", flag);
 		mutex_unlock(&self->io_mutex);
 		return;
 	}

bes2600/bes_pwr.c

@@ -621,19 +621,61 @@ static int bes2600_pwr_enter_lp_mode(struct bes2600_common *hw_priv)
 static void bes2600_pwr_device_exit_lp_mode(struct bes2600_common *hw_priv)
 {
 	int ret = 0;
+	enum bes2600_chip_pm_state state;
 	struct wsm_operational_mode mode = {
 		.power_mode = wsm_power_mode_active,
 		.disableMoreFlagUsage = true,
 	};
 
-	bes_devel("host lock lmac\n");
-	if(hw_priv->sbus_ops->gpio_wake)
-		hw_priv->sbus_ops->gpio_wake(hw_priv->sbus_priv, GPIO_WAKE_FLAG_MCU);
+	/*
+	 * Consult chip_pm_state set by bes2600_pwr_notify_ps_changed().
+	 * If we last saw the firmware confirm ACTIVE, skip ONLY the
+	 * gpio_wake + sbus_active wake handshake - the GPIO is already
+	 * asserted high and the SDIO MCU subsystem is already running,
+	 * so another sbus_active() round-trip just hits its 200x2ms
+	 * timeout because the firmware has nothing to do.
+	 *
+	 * wsm_set_operational_mode() below is NOT part of the wake
+	 * handshake; it is the operational-mode setter the firmware
+	 * tracks per call. Skipping it leaves the chip's SDIO state
+	 * machine without a fresh operational-mode update, which on
+	 * PineTab2 wedges the bus (-EBUSY on next sdio_rx_work read)
+	 * within a few seconds of probe completion. So it must run
+	 * unconditionally.
+	 */
+	state = atomic_read(&hw_priv->bes_power.chip_pm_state);
+	if (state == BES2600_CHIP_PM_ACTIVE) {
+		bes_devel("device_exit_lp_mode: chip already ACTIVE, skipping wake handshake\n");
+	} else {
+		bes_devel("host lock lmac\n");
+		if (hw_priv->sbus_ops->gpio_wake)
+			hw_priv->sbus_ops->gpio_wake(hw_priv->sbus_priv,
+						      GPIO_WAKE_FLAG_MCU);
 
-	if(hw_priv->sbus_ops->sbus_active) {
-		ret = hw_priv->sbus_ops->sbus_active(hw_priv->sbus_priv, SUBSYSTEM_MCU);
-		if (ret)
-			bes_err("%s, active mcu fail\n", __func__);
+		if (hw_priv->sbus_ops->sbus_active) {
+			ret = hw_priv->sbus_ops->sbus_active(hw_priv->sbus_priv,
+							     SUBSYSTEM_MCU);
+			if (ret) {
+				/*
+				 * MCU_WAKEUP_READY did not arrive within
+				 * the SDIO handshake window. Record state
+				 * as UNKNOWN so the next exit_lp_mode call
+				 * also runs the full wake sequence (no
+				 * skip), but still send operational_mode
+				 * below to match pre-c6 behaviour - the
+				 * WSM may succeed even if the SDIO active
+				 * confirm was lost, and if it fails too,
+				 * we just emit a second devel-level error.
+				 * Repeated UNKNOWN is the signal for the
+				 * LMAC active-monitor to eventually
+				 * escalate to bus_reset (c5.2's
+				 * mmc_hw_reset path).
+				 */
+				bes_err("%s, active mcu fail\n", __func__);
+				atomic_set(&hw_priv->bes_power.chip_pm_state,
+					   BES2600_CHIP_PM_UNKNOWN);
+			}
+		}
 	}
 
 	ret = wsm_set_operational_mode(hw_priv, &mode, 0);