Re: [PATCH v5] Fix SSR(SubSystem Restart) fail when BT_EN is pulled up by hw

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Dear,Paul

On 8/20/2025 9:32 PM, Paul Menzel wrote:
> 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
> 
>> Signed-off-by: Shuai Zhang <quic_shuaz@xxxxxxxxxxx>
>> ---
>>   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
Thanks again for your thorough check. 
I’ll revise the content and share the updated version soon


BR,
Shuai







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