Re: [PATCH v5] Fix SSR(SubSystem Restart) fail when BT_EN is pulled up by hw
From: Paul Menzel <hidden>
Date: 2025-08-20 13:41:06
Also in:
linux-arm-msm
Dear Shuai, Thank you for the improved version. The commit message summary/title still has the space missing before the ( and should be prefixed with `Bluetooth:` to pass the linters. Am 20.08.25 um 14:06 schrieb Shuai Zhang:
When the host actively triggers SSR and collects coredump data,
the Bluetooth stack sends a reset command to the controller. However, due
to the inability to clear the QCA_SSR_TRIGGERED and QCA_IBS_DISABLED bits,
the reset command times out.
To address this, this patch clears the QCA_SSR_TRIGGERED and
QCA_IBS_DISABLED flags and adds a 50ms delay after SSR, but only when
HCI_QUIRK_NON_PERSISTENT_SETUP is not set. This ensures the controller
completes the SSR process when BT_EN is always high due to hardware.
For the purpose of HCI_QUIRK_NON_PERSISTENT_SETUP, please refer to
commit 740011cfe948 ("Bluetooth: Add new quirk for non-persistent setup
settings")Missing dot/period at the end. Also, the comment in `include/net/bluetooth/hci.h` is more helpful to me than the commit.
The HCI_QUIRK_NON_PERSISTENT_SETUP quirk is associated with BT_EN, and its presence can be used to determine whether BT_EN is defined in DTS. After SSR, host will not download the firmware, causing controller to remain in the IBS_WAKE state. Host needs to synchronize with the controller to maintain proper operation. Multiple triggers of SSR only first generate coredump file, duo to memcoredump_flag no clear.
due to
add clear coredump flag when ssr completed. When the SSR duration exceeds 2 seconds, it triggers host tx_idle_timeout, which sets host TX state to sleep. due to the hardware pulling up bt_en, the firmware is not downloaded after the SSR. As a result, the controller does not enter sleep mode. Consequently, when the host sends a command afterward, it sends 0xFD to the controller, but the controller does not respond, leading to a command timeout. So reset tx_idle_timer after SSR to prevent host enter TX IBS_Sloeep mode.
Sleep
quoted hunk ↗ jump to hunk
Signed-off-by: Shuai Zhang <redacted> --- drivers/bluetooth/hci_qca.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c index 4e56782b0..403d65952 100644 --- a/drivers/bluetooth/hci_qca.c +++ b/drivers/bluetooth/hci_qca.c@@ -1653,6 +1653,37 @@ 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
Missing space before (.
+ * 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 (!test_bit(HCI_QUIRK_NON_PERSISTENT_SETUP, &hdev->quirks)) {
+ /*
+ * When the SSR (Sub-System 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_Sloeep mode.Sleep?
+ */ + mod_timer(&qca->tx_idle_timer, jiffies + + msecs_to_jiffies(qca->tx_idle_delay)); + msleep(50);
Add a comment, why 50 ms and not 20 ms or 100 ms?
+ + 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); }
Kind regards, Paul