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>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 888176b0faa906ee3f078e75093c037e39bbd89b..a3c217571c3c45fe614755687bc8a87977f35da4 100644 (file)
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -1653,6 +1653,39 @@ static void qca_hw_error(struct hci_dev *hdev, u8 code)
                skb_queue_purge(&qca->rx_memdump_q);
        }
 
+       /*
+        * 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
+        *
+        * 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;
+       }
+
        clear_bit(QCA_HW_ERROR_EVENT, &qca->flags);
 }