staging: vt6656: limit reg output to block size

vnt_control_out appears to fail when BBREG is greater than 64 writes.

Create new function that will relay an array in no larger than
the indicated block size.

It appears that this command has always failed but was ignored by
driver until the introduction of error checking.

Cc: stable <stable@vger.kernel.org> # v5.3+
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Link: https://lore.kernel.org/r/a41f0601-df46-ce6e-ab7c-35e697946e2a@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6656/baseband.c

@@ -449,8 +449,8 @@ int vnt_vt3184_init(struct vnt_private *priv)
 
 	memcpy(array, addr, length);
 
-	ret = vnt_control_out(priv, MESSAGE_TYPE_WRITE, 0,
-			      MESSAGE_REQUEST_BBREG, length, array);
+	ret = vnt_control_out_blocks(priv, VNT_REG_BLOCK_SIZE,
+				     MESSAGE_REQUEST_BBREG, length, array);
 	if (ret)
 		goto end;
 

drivers/staging/vt6656/usbpipe.c

@@ -76,6 +76,23 @@ int vnt_control_out_u8(struct vnt_private *priv, u8 reg, u8 reg_off, u8 data)
 			       reg_off, reg, sizeof(u8), &data);
 }
 
+int vnt_control_out_blocks(struct vnt_private *priv,
+			   u16 block, u8 reg, u16 length, u8 *data)
+{
+	int ret = 0, i;
+
+	for (i = 0; i < length; i += block) {
+		u16 len = min_t(int, length - i, block);
+
+		ret = vnt_control_out(priv, MESSAGE_TYPE_WRITE,
+				      i, reg, len, data + i);
+		if (ret)
+			goto end;
+	}
+end:
+	return ret;
+}
+
 int vnt_control_in(struct vnt_private *priv, u8 request, u16 value,
 		   u16 index, u16 length, u8 *buffer)
 {

drivers/staging/vt6656/usbpipe.h

@@ -18,6 +18,8 @@
 
 #include "device.h"
 
+#define VNT_REG_BLOCK_SIZE	64
+
 int vnt_control_out(struct vnt_private *priv, u8 request, u16 value,
 		    u16 index, u16 length, u8 *buffer);
 int vnt_control_in(struct vnt_private *priv, u8 request, u16 value,
@@ -26,6 +28,9 @@ int vnt_control_in(struct vnt_private *priv, u8 request, u16 value,
 int vnt_control_out_u8(struct vnt_private *priv, u8 reg, u8 ref_off, u8 data);
 int vnt_control_in_u8(struct vnt_private *priv, u8 reg, u8 reg_off, u8 *data);
 
+int vnt_control_out_blocks(struct vnt_private *priv,
+			   u16 block, u8 reg, u16 len, u8 *data);
+
 int vnt_start_interrupt_urb(struct vnt_private *priv);
 int vnt_submit_rx_urb(struct vnt_private *priv, struct vnt_rcb *rcb);
 int vnt_tx_context(struct vnt_private *priv,