[media] af9035: fix and enhance I2C adapter

There was a bug I2C adapter writes and reads one byte too much.
As the most I2C clients has auto-increment register addressing
this leads next register from the target register overwritten by
garbage data.

As a change remove whole register address byte usage and write
data directly to the I2C bus without saying what are register
address bytes to firmware.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Cc: Michael Buesch <m@bues.ch>
Cc: Hans-Frieder Vogt <hfvogt@gmx.net>
Cc: Gianluca Gennari <gennarone@gmail.com>
Tested-by: Michael Buesch <m@bues.ch>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/dvb/dvb-usb/af9035.c b/drivers/media/dvb/dvb-usb/af9035.c
index 73044632d943090daa618edad1dde88b49c7e460..58fe69deda1fe0f6229ae733e81daca120064503 100644 (file)
--- a/drivers/media/dvb/dvb-usb/af9035.c
+++ b/drivers/media/dvb/dvb-usb/af9035.c
@@ -224,6 +224,22 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
        if (mutex_lock_interruptible(&d->i2c_mutex) < 0)
                return -EAGAIN;
 
+       /*
+        * I2C sub header is 5 bytes long. Meaning of those bytes are:
+        * 0: data len
+        * 1: I2C addr << 1
+        * 2: reg addr len
+        *    byte 3 and 4 can be used as reg addr
+        * 3: reg addr MSB
+        *    used when reg addr len is set to 2
+        * 4: reg addr LSB
+        *    used when reg addr len is set to 1 or 2
+        *
+        * For the simplify we do not use register addr at all.
+        * NOTE: As a firmware knows tuner type there is very small possibility
+        * there could be some tuner I2C hacks done by firmware and this may
+        * lead problems if firmware expects those bytes are used.
+        */
        if (num == 2 && !(msg[0].flags & I2C_M_RD) &&
                        (msg[1].flags & I2C_M_RD)) {
                if (msg[0].len > 40 || msg[1].len > 40) {
@@ -237,14 +253,15 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
                                        msg[1].len);
                } else {
                        /* I2C */
-                       u8 buf[4 + msg[0].len];
+                       u8 buf[5 + msg[0].len];
                        struct usb_req req = { CMD_I2C_RD, 0, sizeof(buf),
                                        buf, msg[1].len, msg[1].buf };
                        buf[0] = msg[1].len;
                        buf[1] = msg[0].addr << 1;
-                       buf[2] = 0x01;
-                       buf[3] = 0x00;
-                       memcpy(&buf[4], msg[0].buf, msg[0].len);
+                       buf[2] = 0x00; /* reg addr len */
+                       buf[3] = 0x00; /* reg addr MSB */
+                       buf[4] = 0x00; /* reg addr LSB */
+                       memcpy(&buf[5], msg[0].buf, msg[0].len);
                        ret = af9035_ctrl_msg(d->udev, &req);
                }
        } else if (num == 1 && !(msg[0].flags & I2C_M_RD)) {
@@ -259,14 +276,15 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
                                        msg[0].len - 3);
                } else {
                        /* I2C */
-                       u8 buf[4 + msg[0].len];
+                       u8 buf[5 + msg[0].len];
                        struct usb_req req = { CMD_I2C_WR, 0, sizeof(buf), buf,
                                        0, NULL };
                        buf[0] = msg[0].len;
                        buf[1] = msg[0].addr << 1;
-                       buf[2] = 0x01;
-                       buf[3] = 0x00;
-                       memcpy(&buf[4], msg[0].buf, msg[0].len);
+                       buf[2] = 0x00; /* reg addr len */
+                       buf[3] = 0x00; /* reg addr MSB */
+                       buf[4] = 0x00; /* reg addr LSB */
+                       memcpy(&buf[5], msg[0].buf, msg[0].len);
                        ret = af9035_ctrl_msg(d->udev, &req);
                }
        } else {