linux-kernel - Re: [PATCH v4 2/2] Bluetooth: btusb: Support Bluetooth Reset for Mediatek Chip(MT7921)

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Date:   Thu, 22 Jul 2021 16:03:48 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     "Mark-YW Chen (陳揚文)" 
        <Mark-YW.Chen@...iatek.com>
Cc:     Johan Hedberg <johan.hedberg@...il.com>, chris.lu@...iatek.com,
        will-cy.lee@...iatek.com, Sean Wang <sean.wang@...iatek.com>,
        Bluetooth Kernel Mailing List 
        <linux-bluetooth@...r.kernel.org>,
        linux-mediatek@...ts.infradead.org,
        open list <linux-kernel@...r.kernel.org>,
        michaelfsun@...gle.com, shawnku@...gle.com, jemele@...gle.com,
        apusaka@...gle.com
Subject: Re: [PATCH v4 2/2] Bluetooth: btusb: Support Bluetooth Reset for
 Mediatek Chip(MT7921)

Hi Mark,

> When the firmware hang or command no response, driver can reset the
> bluetooth mcu via USB to recovery it. The reset steps as follows.
> 
> 1. Cancel USB transfer requests before reset.
> 2. It use speicific USB HW Register to reset Bluetooth MCU, at the
>   same time, the USB Endpoint0 still keep alive.
> 3. Poll the USB HW register until reset is completed by Endpoint0.
> 4. To recovery unexpected USB state and behavior during resetting the
>   Bluetooth MCU, the driver need to reset the USB device for MT7921.
> 5. After the reset is completed, the Bluetooth MCU need to re-setup,
>   such as download patch, power-on sequence and etc.
> 
> Signed-off-by: mark-yw.chen <mark-yw.chen@...iatek.com>
> ---
> drivers/bluetooth/btusb.c | 127 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 127 insertions(+)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index b1249b664981..122a928ebcb5 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -3076,6 +3076,17 @@ static int btusb_shutdown_intel_new(struct hci_dev *hdev)
> 	return 0;
> }
> 
> +/* UHW CR mapping */
> +#define BT_MISC			0x70002510
> +#define BT_SUBSYS_RST		0x70002610
> +#define UDMA_INT_STA_BT		0x74000024
> +#define UDMA_INT_STA_BT1	0x74000308
> +#define BT_WDT_STATUS		0x740003A0
> +#define EP_RST_OPT		0x74011890
> +#define EP_RST_IN_OUT_OPT	0x00010001
> +#define BT_RST_DONE		0x00000100
> +#define BT_RESET_WAIT_MS	100
> +#define BT_RESET_NUM_TRIES	10

you need to prefix these with MTK since otherwise we get confused.

And we need to work towards abstracting the vendor specific position out of btusb.c (and I include the Intel part here as well). The btusb.c is getting overloaded with vendor stuff.

Regards

Marcel