V4L/DVB: tm6000: bugfix reading problems with demodulator zl10353

Reading from zl10353 with tm6000 has a bug. For example:

regs  w/o patch  with patch

0x06     0x00        0x7f
0x07     0x33        0x30
0x08     0x00        0x00
0x09     0x58        0x50
0x0f     0x31        0x28
0x10     0x00        0x84

This patch provides the workaround for the bug

[mchehab@redhat.com: Fix merge conflict and add a comment at the workaround]
Signed-off-by: Stefan Ringel <stefan.ringel@arcor.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/tm6000/tm6000-i2c.c

@@ -56,9 +56,23 @@ static int tm6000_i2c_recv_regs(struct tm6000_core *dev, unsigned char addr,
 				__u8 reg, char *buf, int len)
 {
 	int rc;
+	u8 b[2];
 
-	rc = tm6000_read_write_usb(dev, USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+	if ((dev->caps.has_zl10353) && (dev->demod_addr << 1 == addr) && (reg % 2 == 0)) {
+		/*
+		 * Workaround an I2C bug when reading from zl10353
+		 */
+		reg -= 1;
+		len += 1;
+
+		rc = tm6000_read_write_usb(dev, USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			REQ_16_SET_GET_I2C_WR1_RDN, addr | reg << 8, 0, b, len);
+
+		*buf = b[1];
+	} else {
+		rc = tm6000_read_write_usb(dev, USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
 			REQ_16_SET_GET_I2C_WR1_RDN, addr | reg << 8, 0, buf, len);
+	}
 
 	return rc;
 }