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Date: Tue, 27 Feb 2024 13:56:19 +0100
From: Sascha Hauer <sha@pengutronix.de>
To: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	Ping-Ke Shih <pkshih@realtek.com>
Subject: Re: [PATCH 1/4] wifi: rtw88: 8821cu: Fix firmware upload fail
Message-ID: <Zd3b81m3_Hh47lww@pengutronix.de>
References: <731ea688-04ef-4f02-9d01-3e9026981057@gmail.com>
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In-Reply-To: <731ea688-04ef-4f02-9d01-3e9026981057@gmail.com>

On Tue, Feb 27, 2024 at 02:18:20PM +0200, Bitterblue Smith wrote:
> RTL8822CU, RTL8822BU, and RTL8821CU need an extra register write after
> reading and writing certain addresses.
> 
> Without this, the firmware upload fails approximately more than 50% of
> the time.

Great stuff. I have seen these firmware upload failures as well and
couldn't make any sense of it.

> 
> Tested with RTL8811CU (Tenda U9 V2.0) which is the same as RTL8821CU
> but without Bluetooth.
> 
> Fixes: a82dfd33d123 ("wifi: rtw88: Add common USB chip support")
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
> ---
>  drivers/net/wireless/realtek/rtw88/usb.c | 46 ++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
> index 3c4f28c306a9..ff01f7056ca9 100644
> --- a/drivers/net/wireless/realtek/rtw88/usb.c
> +++ b/drivers/net/wireless/realtek/rtw88/usb.c
> @@ -33,6 +33,42 @@ static void rtw_usb_fill_tx_checksum(struct rtw_usb *rtwusb,
>  	rtw_tx_fill_txdesc_checksum(rtwdev, &pkt_info, skb->data);
>  }
>  
> +#define REG_ON_SEC 0x00
> +#define REG_OFF_SEC 0x01
> +#define REG_LOCAL_SEC 0x02
> +
> +static void rtw_usb_reg_sec(struct rtw_dev *rtwdev, u32 addr, __le32 *data)
> +{
> +	struct rtw_usb *rtwusb = rtw_get_usb_priv(rtwdev);
> +	struct usb_device *udev = rtwusb->udev;
> +	u8 current_reg_sec;
> +	u16 t_reg = 0x4e0;
> +	u8 t_len = 1;
> +	int status;
> +
> +	if (addr < 0xFE00) {
> +		if (addr <= 0xff)
> +			current_reg_sec = REG_ON_SEC;
> +		else if (0x1000 <= addr && addr <= 0x10ff)
> +			current_reg_sec = REG_ON_SEC;
> +		else
> +			current_reg_sec = REG_OFF_SEC;
> +	} else {
> +		current_reg_sec = REG_LOCAL_SEC;
> +	}
> +
> +	if (current_reg_sec != REG_ON_SEC)
> +		return;

Is there something we want to do with current_reg_sec == REG_LOCAL_SEC
or current_reg_sec == REG_OFF_SEC later? If not the above could be
rewritten as:

	if (addr > 0xff && addr < 0x1000)
		return;
	if (addr > 0x10ff)
		return;

	...

Sascha

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