[PATCH 08/10] V4L/DVB: tda18271: allow restricting max out to 4 bytes

Mauro Carvalho Chehab
2010-09-28T18:54:37Z

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.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/common/tuners/tda18271-common.c b/drivers/media/common/tuners/tda18271-common.c
index e1f6782..195b30e 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;

- /* write registers */
- ret = i2c_transfer(priv->i2c_props.adap, &msg, 1);
+ buf[0] = idx;
+ for (i = 1; i <= max; i++)
+ buf[i] = regs[idx - 1 + i];

+ 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 d7fcc36..3abb221 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 {
diff --git a/drivers/media/video/tuner-core.c b/drivers/media/video/tuner-core.c
index fa406b9..1a047c5 100644
--- a/drivers/media/video/tuner-core.c
+++ b/drivers/media/video/tuner-core.c
@@ -428,7 +428,7 @@ static void set_type(struct i2c_client *c, unsigned int type,
{
struct tda18271_config cfg = {
.config = t->config,
- .small_i2c = TDA18271_08_BYTE_CHUNK_INIT,
+ .small_i2c = TDA18271_03_BYTE_CHUNK_INIT,
};

if (!dvb_attach(tda18271_attach, &t->fe, t->i2c->addr,
--
1.7.1