V4L/DVB (6633): xc2028: make register reads atomic

Issuing register reads as a separate address write and data read transactions
means that other I2C activity could occur in between and state could get out
of sync.  Issue both the write and read in a single transaction so that the
i2c layer can prevent other users accessing the bus until we are complete.

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

1 files changed, 30 insertions, 25 deletions

diff --git a/drivers/media/video/tuner-xc2028.c b/drivers/media/video/tuner-xc2028.c
index 166fede7d0e3..a49a4e886897 100644
--- a/drivers/media/video/tuner-xc2028.c
+++ b/drivers/media/video/tuner-xc2028.c
@@ -101,6 +101,16 @@ struct xc2028_data {
         _rc;                                                            \
 })
 
+#define i2c_send_recv(priv, obuf, osize, ibuf, isize) ({                \
+        int _rc;                                                        \
+        _rc = tuner_i2c_xfer_send_recv(&priv->i2c_props, obuf, osize,   \
+                                       ibuf, isize);                    \
+        if (isize != _rc)                                               \
+                tuner_err("i2c input error: rc = %d (should be %d)\n",  \
+                           _rc, (int)isize);                            \
+        _rc;                                                            \
+})
+
 #define send_seq(priv, data...) ({                                      \
         static u8 _val[] = data;                                        \
         int _rc;                                                        \
@@ -113,25 +123,21 @@ struct xc2028_data {
         _rc;                                                            \
 })
 
-static unsigned int xc2028_get_reg(struct xc2028_data *priv, u16 reg)
+static unsigned int xc2028_get_reg(struct xc2028_data *priv, u16 reg, u16 *val)
 {
-        int rc;
         unsigned char buf[2];
+        unsigned char ibuf[2];
 
-        tuner_dbg("%s called\n", __FUNCTION__);
+        tuner_dbg("%s %04x called\n", __FUNCTION__, reg);
 
-        buf[0] = reg>>8;
+        buf[0] = reg >> 8;
         buf[1] = (unsigned char) reg;
 
-        rc = i2c_send(priv, buf, 2);
-        if (rc < 0)
-                return rc;
-
-        rc = i2c_rcv(priv, buf, 2);
-        if (rc < 0)
-                return rc;
+        if (i2c_send_recv(priv, buf, 2, ibuf, 2) != 2)
+                return -EIO;
 
-        return (buf[1]) | (buf[0] << 8);
+        *val = (ibuf[1]) | (ibuf[0] << 8);
+        return 0;
 }
 
 void dump_firm_type(unsigned int type)
@@ -567,7 +573,8 @@ static int check_firmware(struct dvb_frontend *fe, enum tuner_mode new_mode,
                           v4l2_std_id std, fe_bandwidth_t bandwidth)
 {
         struct xc2028_data      *priv = fe->tuner_priv;
-        int                     rc, version, hwmodel;
+        int                     rc;
+        u16                     version, hwmodel;
         v4l2_std_id             std0 = 0;
         unsigned int            type0 = 0, type = 0;
         int                     change_digital_bandwidth;
@@ -692,8 +699,8 @@ static int check_firmware(struct dvb_frontend *fe, enum tuner_mode new_mode,
 
         rc = load_scode(fe, type, &std, 0);
 
-        version = xc2028_get_reg(priv, 0x0004);
-        hwmodel = xc2028_get_reg(priv, 0x0008);
+        xc2028_get_reg(priv, 0x0004, &version);
+        xc2028_get_reg(priv, 0x0008, &hwmodel);
 
         tuner_info("Device is Xceive %d version %d.%d, "
                    "firmware version %d.%d\n",
@@ -708,33 +715,31 @@ static int check_firmware(struct dvb_frontend *fe, enum tuner_mode new_mode,
 static int xc2028_signal(struct dvb_frontend *fe, u16 *strength)
 {
         struct xc2028_data *priv = fe->tuner_priv;
-        int                frq_lock, signal = 0;
+        u16                 frq_lock, signal = 0;
+        int                 rc;
 
         tuner_dbg("%s called\n", __FUNCTION__);
 
         mutex_lock(&priv->lock);
 
-        *strength = 0;
-
         /* Sync Lock Indicator */
-        frq_lock = xc2028_get_reg(priv, 0x0002);
-        if (frq_lock <= 0)
+        rc = xc2028_get_reg(priv, 0x0002, &frq_lock);
+        if (rc < 0 || frq_lock == 0)
                 goto ret;
 
         /* Frequency is locked. Return signal quality */
 
         /* Get SNR of the video signal */
-        signal = xc2028_get_reg(priv, 0x0040);
-
-        if (signal <= 0)
-                signal = frq_lock;
+        rc = xc2028_get_reg(priv, 0x0040, &signal);
+        if (rc < 0)
+                signal = -frq_lock;
 
 ret:
         mutex_unlock(&priv->lock);
 
         *strength = signal;
 
-        return 0;
+        return rc;
 }
 
 #define DIV 15625