linux-kernel - Re: [PATCH v11] Bluetooth: hci_qca: Fix SSR (SubSystem Restart) fail when BT

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Message-ID: <c040b551-17cd-4491-883a-bf33b4ce28f7@quicinc.com>
Date: Mon, 15 Sep 2025 11:04:29 +0800
From: Shuai Zhang <quic_shuaz@...cinc.com>
To: <dmitry.baryshkov@....qualcomm.com>, <marcel@...tmann.org>,
        <luiz.dentz@...il.com>
CC: <linux-bluetooth@...r.kernel.org>, <stable@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_chejiang@...cinc.com>
Subject: Re: [PATCH v11] Bluetooth: hci_qca: Fix SSR (SubSystem Restart) fail
 when BT_EN is pulled up by hw

Hi 

On 8/27/2025 6:25 PM, Shuai Zhang wrote:
> 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
> the comment in `include/net/bluetooth/hci.h`.
> 
> 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,
> due to memcoredump_flag no clear.
> 
> 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_Sleep mode.
> 
> ---
> Changs since v10:
> -- Update base patch to latest patch.
> 
> Changs since v8-v9:
> -- Update base patch to latest patch.
> -- add Cc stable@...r.kernel.org on signed-of.
> 
> Changes since v6-7:
> - Merge the changes into a single patch.
> - Update commit.
> 
> Changes since v1-5:
> - Add an explanation for HCI_QUIRK_NON_PERSISTENT_SETUP.
> - Add commments for msleep(50).
> - Update format and commit.
> 
> Signed-off-by: Shuai Zhang <quic_shuaz@...cinc.com>
> Cc: stable@...r.kernel.org
> ---
>  drivers/bluetooth/hci_qca.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index 4cff4d9be..2d6560482 100644
> --- 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);
>  }
>  

is there any update?

BR,
Shuai