[media] tda18271: allow restricting max out to 4 bytes

By default, tda18271 tries to optimize I2C bus by updating all registers
at the same time. Unfortunately, some devices doesn't support it.

The current logic has a problem when small_i2c is equal to 8, since there
are some transfers using 11 + 1 bytes.

Fix the problem by enforcing the max size at the right place, and allows
reducing it to max = 3 + 1.

Acked-by: Michael Krufky <mkrufky@kernellabs.com>
Acked-by: Sri Deevi <Srinivasa.Deevi@conexant.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 37 insertions, 27 deletions

diff --git a/drivers/media/common/tuners/tda18271-common.c b/drivers/media/common/tuners/tda18271-common.c
index e1f678281a58..195b30e3872d 100644
--- a/drivers/media/common/tuners/tda18271-common.c
+++ b/drivers/media/common/tuners/tda18271-common.c
@@ -193,20 +193,46 @@ int tda18271_write_regs(struct dvb_frontend *fe, int idx, int len)
         unsigned char *regs = priv->tda18271_regs;
         unsigned char buf[TDA18271_NUM_REGS + 1];
         struct i2c_msg msg = { .addr = priv->i2c_props.addr, .flags = 0,
-                               .buf = buf, .len = len + 1 };
-        int i, ret;
+                               .buf = buf };
+        int i, ret = 1, max;
 
         BUG_ON((len == 0) || (idx + len > sizeof(buf)));
 
-        buf[0] = idx;
-        for (i = 1; i <= len; i++)
-                buf[i] = regs[idx - 1 + i];
+
+        switch (priv->small_i2c) {
+        case TDA18271_03_BYTE_CHUNK_INIT:
+                max = 3;
+                break;
+        case TDA18271_08_BYTE_CHUNK_INIT:
+                max = 8;
+                break;
+        case TDA18271_16_BYTE_CHUNK_INIT:
+                max = 16;
+                break;
+        case TDA18271_39_BYTE_CHUNK_INIT:
+        default:
+                max = 39;
+        }
 
         tda18271_i2c_gate_ctrl(fe, 1);
+        while (len) {
+                if (max > len)
+                        max = len;
+
+                buf[0] = idx;
+                for (i = 1; i <= max; i++)
+                        buf[i] = regs[idx - 1 + i];
 
-        /* write registers */
-        ret = i2c_transfer(priv->i2c_props.adap, &msg, 1);
+                msg.len = max + 1;
 
+                /* write registers */
+                ret = i2c_transfer(priv->i2c_props.adap, &msg, 1);
+                if (ret != 1)
+                        break;
+
+                idx += max;
+                len -= max;
+        }
         tda18271_i2c_gate_ctrl(fe, 0);
 
         if (ret != 1)
@@ -326,24 +352,7 @@ int tda18271_init_regs(struct dvb_frontend *fe)
         regs[R_EB22] = 0x48;
         regs[R_EB23] = 0xb0;
 
-        switch (priv->small_i2c) {
-        case TDA18271_08_BYTE_CHUNK_INIT:
-                tda18271_write_regs(fe, 0x00, 0x08);
-                tda18271_write_regs(fe, 0x08, 0x08);
-                tda18271_write_regs(fe, 0x10, 0x08);
-                tda18271_write_regs(fe, 0x18, 0x08);
-                tda18271_write_regs(fe, 0x20, 0x07);
-                break;
-        case TDA18271_16_BYTE_CHUNK_INIT:
-                tda18271_write_regs(fe, 0x00, 0x10);
-                tda18271_write_regs(fe, 0x10, 0x10);
-                tda18271_write_regs(fe, 0x20, 0x07);
-                break;
-        case TDA18271_39_BYTE_CHUNK_INIT:
-        default:
-                tda18271_write_regs(fe, 0x00, TDA18271_NUM_REGS);
-                break;
-        }
+        tda18271_write_regs(fe, 0x00, TDA18271_NUM_REGS);
 
         /* setup agc1 gain */
         regs[R_EB17] = 0x00;
diff --git a/drivers/media/common/tuners/tda18271.h b/drivers/media/common/tuners/tda18271.h
index d7fcc36dc6e6..3abb221f3d07 100644
--- a/drivers/media/common/tuners/tda18271.h
+++ b/drivers/media/common/tuners/tda18271.h
@@ -80,8 +80,9 @@ enum tda18271_output_options {
 
 enum tda18271_small_i2c {
         TDA18271_39_BYTE_CHUNK_INIT = 0,
-        TDA18271_16_BYTE_CHUNK_INIT = 1,
-        TDA18271_08_BYTE_CHUNK_INIT = 2,
+        TDA18271_16_BYTE_CHUNK_INIT = 16,
+        TDA18271_08_BYTE_CHUNK_INIT = 8,
+        TDA18271_03_BYTE_CHUNK_INIT = 3,
 };
 
 struct tda18271_config {