BACKPORT: driver: bluetooth: hci_qca: Fix SSR (SubSystem Restart) fail when BT_EN is pulled up by hw

On QCS9075 and QCA8275 platforms, the BT_EN pin is always pulled up by hw
and cannot be controlled by the host. As a result, in case of a firmware
crash, the host cannot trigger a cold reset. Instead, the BT controller
performs a warm restart on its own, without reloading the firmware.

This leads to the controller remaining in IBS_WAKE state, while the host
expects it to be in sleep mode. The mismatch causes HCI reset commands
to time out. Additionally, the driver does not clear internal flags
QCA_SSR_TRIGGERED and QCA_IBS_DISABLED, which blocks the reset sequence.
If the SSR duration exceeds 2 seconds, the host may enter TX sleep mode
due to tx_idle_timeout, further preventing recovery. Also, memcoredump_flag
is not cleared, so only the first SSR generates a coredump.

Tell the driver that the BT controller has undergone a proper restart
sequence:

- Clear QCA_SSR_TRIGGERED and QCA_IBS_DISABLED flags after SSR.
- Add a 50ms delay to allow the controller to complete its warm reset.
- Reset tx_idle_timer to prevent the host from entering TX sleep mode.
- Clear memcoredump_flag to allow multiple coredump captures.

Apply these steps only when HCI_QUIRK_NON_PERSISTENT_SETUP is not set,
which indicates that BT_EN is defined in DTS and cannot be toggled.

Refer to the comment in include/net/bluetooth/hci.h for details on
HCI_QUIRK_NON_PERSISTENT_SETUP.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Shuai Zhang <shuai.zhang@oss.qualcomm.com>
link: https://lore.kernel.org/all/20251203033712.446632-1-shuai.zhang@oss.qualcomm.com/

Author: shuaz-shuai

drivers/bluetooth/hci_qca.c

@@ -1653,25 +1653,40 @@ static void qca_hw_error(struct hci_dev *hdev, u8 code)
 		skb_queue_purge(&qca->rx_memdump_q);
 	}
 
-	clear_bit(QCA_HW_ERROR_EVENT, &qca->flags);
-
 	/*
-	 * If the SoC always enables the bt_en pin via hardware and the driver
-	 * cannot control the bt_en pin of the SoC chip, then during SSR,
-	 * the QCA_SSR_TRIGGERED and QCA_IBS_DISABLED bits cannot be cleared.
-	 * This leads to a reset command timeout failure.
+	 * If the BT chip's bt_en pin is connected to a 3.3V power supply via
+	 * hardware and always stays high, driver cannot control the bt_en pin.
+	 * As a result, during SSR (SubSystem Restart), QCA_SSR_TRIGGERED and
+	 * QCA_IBS_DISABLED flags cannot be cleared, which leads to a reset
+	 * command timeout.
+	 * Add an msleep delay to ensure controller completes the SSR process.
+	 *
+	 * Host will not download the firmware after SSR, controller to remain
+	 * in the IBS_WAKE state, and the host needs to synchronize with it
 	 *
-	 * To address this, clear QCA_SSR_TRIGGERED and QCA_IBS_DISABLED bits
-	 * after the coredump collection is complete.
-	 * Also, add msleep delay to wait for controller to complete SSR.
+	 * Since the bluetooth chip has been reset, clear the memdump state.
 	 */
 	if (!hci_test_quirk(hu->hdev, HCI_QUIRK_NON_PERSISTENT_SETUP)) {
+		/*
+		 * When the SSR (SubSystem Restart) duration exceeds 2 seconds,
+		 * it triggers host tx_idle_delay, which sets host TX state
+		 * to sleep. Reset tx_idle_timer after SSR to prevent
+		 * host enter TX IBS_Sleep mode.
+		 */
+		mod_timer(&qca->tx_idle_timer, jiffies +
+				  msecs_to_jiffies(qca->tx_idle_delay));
+
+		/* Controller reset completion time is 50ms */
+		msleep(50);
+
 		clear_bit(QCA_SSR_TRIGGERED, &qca->flags);
 		clear_bit(QCA_IBS_DISABLED, &qca->flags);
+
 		qca->tx_ibs_state = HCI_IBS_TX_AWAKE;
 		qca->memdump_state = QCA_MEMDUMP_IDLE;
-		msleep(50);
 	}
+
+	clear_bit(QCA_HW_ERROR_EVENT, &qca->flags);
 }
 
 static void qca_reset(struct hci_dev *hdev)