V4L/DVB (6626): CXUSB: support only-read i2c requests

Any i2c read request that was not immediately preceded by a write request was
incorrectly taking the write path.  Add the capability to handle individual
read requests.

Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/media/dvb/dvb-usb/cxusb.c b/drivers/media/dvb/dvb-usb/cxusb.c
index 86fbd6c73ea9..016a3780b714 100644
--- a/drivers/media/dvb/dvb-usb/cxusb.c
+++ b/drivers/media/dvb/dvb-usb/cxusb.c
@@ -98,8 +98,21 @@ static int cxusb_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[],
                                 break;
                         }
 
-                /* read request */
-                if (i+1 < num && (msg[i+1].flags & I2C_M_RD)) {
+                if (msg[i].flags & I2C_M_RD) {
+                        /* read only */
+                        u8 obuf[3], ibuf[1+msg[i].len];
+                        obuf[0] = 0;
+                        obuf[1] = msg[i].len;
+                        obuf[2] = msg[i].addr;
+                        if (cxusb_ctrl_msg(d, CMD_I2C_READ,
+                                           obuf, 3,
+                                           ibuf, 1+msg[i].len) < 0) {
+                                warn("i2c read failed");
+                                break;
+                        }
+                        memcpy(msg[i].buf, &ibuf[1], msg[i].len);
+                } else if (i+1 < num && (msg[i+1].flags & I2C_M_RD)) {
+                        /* write then read */
                         u8 obuf[3+msg[i].len], ibuf[1+msg[i+1].len];
                         obuf[0] = msg[i].len;
                         obuf[1] = msg[i+1].len;
@@ -117,7 +130,8 @@ static int cxusb_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[],
                         memcpy(msg[i+1].buf, &ibuf[1], msg[i+1].len);
 
                         i++;
-                } else { /* write */
+                } else {
+                        /* write only */
                         u8 obuf[2+msg[i].len], ibuf;
                         obuf[0] = msg[i].addr;
                         obuf[1] = msg[i].len;