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Message-ID: <f806007e-8fba-4f29-8a38-f81d04bd4fb8@gmail.com>
Date: Fri, 29 Dec 2023 22:51:18 +0200
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To: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Cc: Ping-Ke Shih <pkshih@realtek.com>,
 Larry Finger <Larry.Finger@lwfinger.net>
From: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Subject: [PATCH] wifi: rtlwifi: rtl_usb: Use sync register writes
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Currently rtl_usb performs register writes using the async
usb_submit_urb() function. This appears to work fine for the RTL8192CU,
but the RTL8192DU (soon to be supported by rtlwifi) has a problem:
it transmits everything at the 1M rate in the 2.4 GHz band. (The 5 GHZ
band is still untested.)

With this patch, rtl_usb performs the register writes using the
synchronous usb_control_msg() function, and the RTL8192DU works
normally. The RTL8192CU still works.

The vendor drivers use the async writes in only one function,
rtl8192du_trigger_gpio_0 / rtl8192cu_trigger_gpio_0, which probably
doesn't even run in real life. They use sync writes everywhere else.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---

Larry, do you remember why, back in 2011, you chose to implement the
async writes?

I'm not happy about this part:

+	rtlpriv->io.write8_async	= _usb_write8_sync;

The variables say "async" but the functions are not async anymore.
But I couldn't think of a good way to avoid this.

---
 drivers/net/wireless/realtek/rtlwifi/usb.c | 157 ++++++---------------
 1 file changed, 42 insertions(+), 115 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/usb.c b/drivers/net/wireless/realtek/rtlwifi/usb.c
index 30bf2775a335..25394ef702c8 100644
--- a/drivers/net/wireless/realtek/rtlwifi/usb.c
+++ b/drivers/net/wireless/realtek/rtlwifi/usb.c
@@ -23,86 +23,23 @@ MODULE_DESCRIPTION("USB basic driver for rtlwifi");
 
 #define MAX_USBCTRL_VENDORREQ_TIMES		10
 
-static void usbctrl_async_callback(struct urb *urb)
-{
-	if (urb) {
-		/* free dr */
-		kfree(urb->setup_packet);
-		/* free databuf */
-		kfree(urb->transfer_buffer);
-	}
-}
-
-static int _usbctrl_vendorreq_async_write(struct usb_device *udev, u8 request,
-					  u16 value, u16 index, void *pdata,
-					  u16 len)
-{
-	int rc;
-	unsigned int pipe;
-	u8 reqtype;
-	struct usb_ctrlrequest *dr;
-	struct urb *urb;
-	const u16 databuf_maxlen = REALTEK_USB_VENQT_MAX_BUF_SIZE;
-	u8 *databuf;
-
-	if (WARN_ON_ONCE(len > databuf_maxlen))
-		len = databuf_maxlen;
-
-	pipe = usb_sndctrlpipe(udev, 0); /* write_out */
-	reqtype =  REALTEK_USB_VENQT_WRITE;
-
-	dr = kzalloc(sizeof(*dr), GFP_ATOMIC);
-	if (!dr)
-		return -ENOMEM;
-
-	databuf = kzalloc(databuf_maxlen, GFP_ATOMIC);
-	if (!databuf) {
-		kfree(dr);
-		return -ENOMEM;
-	}
-
-	urb = usb_alloc_urb(0, GFP_ATOMIC);
-	if (!urb) {
-		kfree(databuf);
-		kfree(dr);
-		return -ENOMEM;
-	}
-
-	dr->bRequestType = reqtype;
-	dr->bRequest = request;
-	dr->wValue = cpu_to_le16(value);
-	dr->wIndex = cpu_to_le16(index);
-	dr->wLength = cpu_to_le16(len);
-	/* data are already in little-endian order */
-	memcpy(databuf, pdata, len);
-	usb_fill_control_urb(urb, udev, pipe,
-			     (unsigned char *)dr, databuf, len,
-			     usbctrl_async_callback, NULL);
-	rc = usb_submit_urb(urb, GFP_ATOMIC);
-	if (rc < 0) {
-		kfree(databuf);
-		kfree(dr);
-	}
-	usb_free_urb(urb);
-	return rc;
-}
-
-static int _usbctrl_vendorreq_sync_read(struct usb_device *udev, u8 request,
-					u16 value, u16 index, void *pdata,
-					u16 len)
+static void _usbctrl_vendorreq_sync(struct usb_device *udev, u8 reqtype,
+				   u16 value, void *pdata, u16 len)
 {
 	unsigned int pipe;
 	int status;
-	u8 reqtype;
 	int vendorreq_times = 0;
 	static int count;
 
-	pipe = usb_rcvctrlpipe(udev, 0); /* read_in */
-	reqtype =  REALTEK_USB_VENQT_READ;
+	if (reqtype == REALTEK_USB_VENQT_READ)
+		pipe = usb_rcvctrlpipe(udev, 0); /* read_in */
+	else
+		pipe = usb_sndctrlpipe(udev, 0); /* write_out */
 
 	do {
-		status = usb_control_msg(udev, pipe, request, reqtype, value,
-					 index, pdata, len, 1000);
+		status = usb_control_msg(udev, pipe, REALTEK_USB_VENQT_CMD_REQ,
+					 reqtype, value, REALTEK_USB_VENQT_CMD_IDX,
+					 pdata, len, 1000);
 		if (status < 0) {
 			/* firmware download is checksumed, don't retry */
 			if ((value >= FW_8192C_START_ADDRESS &&
@@ -114,18 +51,15 @@ static int _usbctrl_vendorreq_sync_read(struct usb_device *udev, u8 request,
 	} while (++vendorreq_times < MAX_USBCTRL_VENDORREQ_TIMES);
 
 	if (status < 0 && count++ < 4)
-		pr_err("reg 0x%x, usbctrl_vendorreq TimeOut! status:0x%x value=0x%x\n",
-		       value, status, *(u32 *)pdata);
-	return status;
+		pr_err("reg 0x%x, usbctrl_vendorreq TimeOut! status:0x%x value=0x%x reqtype=0x%x\n",
+		       value, status, *(u32 *)pdata, reqtype);
 }
 
 static u32 _usb_read_sync(struct rtl_priv *rtlpriv, u32 addr, u16 len)
 {
 	struct device *dev = rtlpriv->io.dev;
 	struct usb_device *udev = to_usb_device(dev);
-	u8 request;
 	u16 wvalue;
-	u16 index;
 	__le32 *data;
 	unsigned long flags;
 
@@ -134,14 +68,33 @@ static u32 _usb_read_sync(struct rtl_priv *rtlpriv, u32 addr, u16 len)
 		rtlpriv->usb_data_index = 0;
 	data = &rtlpriv->usb_data[rtlpriv->usb_data_index];
 	spin_unlock_irqrestore(&rtlpriv->locks.usb_lock, flags);
-	request = REALTEK_USB_VENQT_CMD_REQ;
-	index = REALTEK_USB_VENQT_CMD_IDX; /* n/a */
 
 	wvalue = (u16)addr;
-	_usbctrl_vendorreq_sync_read(udev, request, wvalue, index, data, len);
+	_usbctrl_vendorreq_sync(udev, REALTEK_USB_VENQT_READ, wvalue, data, len);
 	return le32_to_cpu(*data);
 }
 
+
+static void _usb_write_sync(struct rtl_priv *rtlpriv, u32 addr, u32 val, u16 len)
+{
+	struct device *dev = rtlpriv->io.dev;
+	struct usb_device *udev = to_usb_device(dev);
+	unsigned long flags;
+	__le32 *data;
+	u16 wvalue;
+
+	spin_lock_irqsave(&rtlpriv->locks.usb_lock, flags);
+	if (++rtlpriv->usb_data_index >= RTL_USB_MAX_RX_COUNT)
+		rtlpriv->usb_data_index = 0;
+	data = &rtlpriv->usb_data[rtlpriv->usb_data_index];
+	spin_unlock_irqrestore(&rtlpriv->locks.usb_lock, flags);
+
+	wvalue = (u16)(addr & 0x0000ffff);
+	*data = cpu_to_le32(val);
+
+	_usbctrl_vendorreq_sync(udev, REALTEK_USB_VENQT_WRITE, wvalue, data, len);
+}
+
 static u8 _usb_read8_sync(struct rtl_priv *rtlpriv, u32 addr)
 {
 	return (u8)_usb_read_sync(rtlpriv, addr, 1);
@@ -157,45 +110,19 @@ static u32 _usb_read32_sync(struct rtl_priv *rtlpriv, u32 addr)
 	return _usb_read_sync(rtlpriv, addr, 4);
 }
 
-static void _usb_write_async(struct usb_device *udev, u32 addr, u32 val,
-			     u16 len)
-{
-	u8 request;
-	u16 wvalue;
-	u16 index;
-	__le32 data;
-	int ret;
-
-	request = REALTEK_USB_VENQT_CMD_REQ;
-	index = REALTEK_USB_VENQT_CMD_IDX; /* n/a */
-	wvalue = (u16)(addr&0x0000ffff);
-	data = cpu_to_le32(val);
-
-	ret = _usbctrl_vendorreq_async_write(udev, request, wvalue,
-					     index, &data, len);
-	if (ret < 0)
-		dev_err(&udev->dev, "error %d writing at 0x%x\n", ret, addr);
-}
-
-static void _usb_write8_async(struct rtl_priv *rtlpriv, u32 addr, u8 val)
+static void _usb_write8_sync(struct rtl_priv *rtlpriv, u32 addr, u8 val)
 {
-	struct device *dev = rtlpriv->io.dev;
-
-	_usb_write_async(to_usb_device(dev), addr, val, 1);
+	_usb_write_sync(rtlpriv, addr, val, 1);
 }
 
-static void _usb_write16_async(struct rtl_priv *rtlpriv, u32 addr, u16 val)
+static void _usb_write16_sync(struct rtl_priv *rtlpriv, u32 addr, u16 val)
 {
-	struct device *dev = rtlpriv->io.dev;
-
-	_usb_write_async(to_usb_device(dev), addr, val, 2);
+	_usb_write_sync(rtlpriv, addr, val, 2);
 }
 
-static void _usb_write32_async(struct rtl_priv *rtlpriv, u32 addr, u32 val)
+static void _usb_write32_sync(struct rtl_priv *rtlpriv, u32 addr, u32 val)
 {
-	struct device *dev = rtlpriv->io.dev;
-
-	_usb_write_async(to_usb_device(dev), addr, val, 4);
+	_usb_write_sync(rtlpriv, addr, val, 4);
 }
 
 static void _rtl_usb_io_handler_init(struct device *dev,
@@ -205,9 +132,9 @@ static void _rtl_usb_io_handler_init(struct device *dev,
 
 	rtlpriv->io.dev = dev;
 	mutex_init(&rtlpriv->io.bb_mutex);
-	rtlpriv->io.write8_async	= _usb_write8_async;
-	rtlpriv->io.write16_async	= _usb_write16_async;
-	rtlpriv->io.write32_async	= _usb_write32_async;
+	rtlpriv->io.write8_async	= _usb_write8_sync;
+	rtlpriv->io.write16_async	= _usb_write16_sync;
+	rtlpriv->io.write32_async	= _usb_write32_sync;
 	rtlpriv->io.read8_sync		= _usb_read8_sync;
 	rtlpriv->io.read16_sync		= _usb_read16_sync;
 	rtlpriv->io.read32_sync		= _usb_read32_sync;
-- 
2.43.0