linux-kernel - Re: [PATCH v2 2/2] Bluetooth: btusb: mediatek: add a recovery method for MT7922 and MT7925

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Date: Fri, 2 Feb 2024 18:39:00 -0600
From: Sean Wang <sean.wang@...nel.org>
To: Hao Qin <hao.qin@...iatek.com>
Cc: Marcel Holtmann <marcel@...tmann.org>, Johan Hedberg <johan.hedberg@...il.com>, 
	Luiz Von Dentz <luiz.dentz@...il.com>, Sean Wang <sean.wang@...iatek.com>, 
	Deren Wu <deren.Wu@...iatek.com>, Aaron Hou <aaron.hou@...iatek.com>, 
	Chris Lu <chris.lu@...iatek.com>, Steve Lee <steve.lee@...iatek.com>, 
	linux-bluetooth <linux-bluetooth@...r.kernel.org>, 
	linux-kernel <linux-kernel@...r.kernel.org>, 
	linux-mediatek <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v2 2/2] Bluetooth: btusb: mediatek: add a recovery method
 for MT7922 and MT7925

On Tue, Jan 2, 2024 at 6:49 AM Hao Qin <hao.qin@...iatek.com> wrote:
>
> From: "hao.qin" <hao.qin@...iatek.com>
>
> For MT7922 and MT7925, add USB reset retry to recover from patch
> download failure, and perform a reset before patch download to
> avoid unexpected problems caused by unkonwn status of dongle.
>
> Signed-off-by: hao.qin <hao.qin@...iatek.com>
> ---
>  drivers/bluetooth/btusb.c | 29 ++++++++++++++++++++++++-----
>  1 file changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index abefcd1a089d..26ad4864d06c 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -3000,17 +3000,26 @@ static int btusb_mtk_subsys_reset(struct hci_dev *hdev, u32 dev_id)
>         u32 val;
>         int err;
>
> -       if (dev_id == 0x7925) {
> +       if (dev_id == 0x7922) {
> +               btusb_mtk_uhw_reg_read(data, MTK_BT_SUBSYS_RST, &val);
> +               val |= 0x00002020;
> +               btusb_mtk_uhw_reg_write(data, MTK_BT_SUBSYS_RST, val);
> +               btusb_mtk_uhw_reg_write(data, MTK_EP_RST_OPT, 0x00010001);
> +               btusb_mtk_uhw_reg_read(data, MTK_BT_SUBSYS_RST, &val);
> +               val |= BIT(0);
> +               btusb_mtk_uhw_reg_write(data, MTK_BT_SUBSYS_RST, val);
> +               msleep(100);
> +       } else if (dev_id == 0x7925) {
>                 btusb_mtk_uhw_reg_read(data, MTK_BT_RESET_REG_CONNV3, &val);
> -               val |= (1 << 5);
> +               val |= BIT(5);
>                 btusb_mtk_uhw_reg_write(data, MTK_BT_RESET_REG_CONNV3, val);
>                 btusb_mtk_uhw_reg_read(data, MTK_BT_RESET_REG_CONNV3, &val);
>                 val &= 0xFFFF00FF;
> -               val |= (1 << 13);
> +               val |= BIT(13);
>                 btusb_mtk_uhw_reg_write(data, MTK_BT_RESET_REG_CONNV3, val);
>                 btusb_mtk_uhw_reg_write(data, MTK_EP_RST_OPT, 0x00010001);
>                 btusb_mtk_uhw_reg_read(data, MTK_BT_RESET_REG_CONNV3, &val);
> -               val |= (1 << 0);
> +               val |= BIT(0);
>                 btusb_mtk_uhw_reg_write(data, MTK_BT_RESET_REG_CONNV3, val);
>                 btusb_mtk_uhw_reg_write(data, MTK_UDMA_INT_STA_BT, 0x000000FF);
>                 btusb_mtk_uhw_reg_read(data, MTK_UDMA_INT_STA_BT, &val);
> @@ -3040,6 +3049,9 @@ static int btusb_mtk_subsys_reset(struct hci_dev *hdev, u32 dev_id)
>         if (err < 0)
>                 bt_dev_err(hdev, "Reset timeout");
>
> +       if (dev_id == 0x7922)
> +               btusb_mtk_uhw_reg_write(data, MTK_UDMA_INT_STA_BT, 0x000000FF);
> +
>         btusb_mtk_id_get(data, 0x70010200, &val);
>         if (!val)
>                 bt_dev_err(hdev, "Can't get device id, subsys reset fail.");
> @@ -3128,8 +3140,10 @@ static int btusb_mtk_setup(struct hci_dev *hdev)
>                 fwname = FIRMWARE_MT7668;
>                 break;
>         case 0x7922:
> -       case 0x7961:
>         case 0x7925:
> +               btusb_mtk_subsys_reset(hdev, dev_id);

Is there any reason we cannot perform a subsystem reset for 0x7961?
I believe it would enhance robustness under any circumstance, such as
cold reboot, warm reboot, or suspension,
ensuring that the controller can be reset to its initial state

> +               fallthrough;
> +       case 0x7961:
>                 if (dev_id == 0x7925)
>                         snprintf(fw_bin_name, sizeof(fw_bin_name),
>                                  "mediatek/mt%04x/BT_RAM_CODE_MT%04x_1_%x_hdr.bin",
> @@ -3143,6 +3157,11 @@ static int btusb_mtk_setup(struct hci_dev *hdev)
>                                                 btusb_mtk_hci_wmt_sync);
>                 if (err < 0) {
>                         bt_dev_err(hdev, "Failed to set up firmware (%d)", err);
> +                       if (dev_id == 0x7922 || dev_id == 0x7925) {

Similarly, is there any reason we cannot apply the same approach for
mt7961? Using a less specific condition would reduce maintenance
effort in the future.

> +                               btusb_stop_traffic(data);
> +                               usb_kill_anchored_urbs(&data->tx_anchor);
> +                               usb_queue_reset_device(data->intf);

If an error occurs during firmware download, I guess we can
subsequently attempt to download the firmware again through several
retries.
This helps the controller to autonomously recover from any potential
errors and ensure we can complete the initialization process.

> +                       }
>                         return err;
>                 }
>
> --
> 2.18.0
>
>