On 02.01.2014 20:20, Mauro Carvalho Chehab wrote:
Em Wed, 01 Jan 2014 19:52:08 +0100
Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu:
Am 28.12.2013 13:16, schrieb Mauro Carvalho Chehab:
From: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Instead of using two I2C operations between write and read,
use just one i2c_transfer. That allows I2C mutexes to not
let any other I2C transfer between the two.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
---
drivers/media/i2c/tvp5150.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/drivers/media/i2c/tvp5150.c b/drivers/media/i2c/tvp5150.c
index 89c0b13463b7..d6ba457fcf67 100644
--- a/drivers/media/i2c/tvp5150.c
+++ b/drivers/media/i2c/tvp5150.c
@@ -58,21 +58,19 @@ static int tvp5150_read(struct v4l2_subdev *sd, unsigned char addr)
struct i2c_client *c = v4l2_get_subdevdata(sd);
unsigned char buffer[1];
int rc;
+ struct i2c_msg msg[] = {
+ { .addr = c->addr, .flags = 0,
+ .buf = &addr, .len = 1 },
I would use .buf = buffer here, too.
Why? The address needed is already at addr, and it is also an unsigned char.
Using buffer would require an extra data copy.
You are still doing this...
+ { .addr = c->addr, .flags = I2C_M_RD,
+ .buf = buffer, .len = 1 }
+ };
buffer[0] = addr;
... here. ;)
- rc = i2c_master_send(c, buffer, 1);
- if (rc < 0) {
- v4l2_err(sd, "i2c i/o error: rc == %d (should be 1)\n", rc);
- return rc;
- }
-
- msleep(10);
That's the critical change.
I don't think so. I'm not sure why I added this at the first place on the
original patch with where I added this driver, but it is very doubtful
that a msleep() is needed here.
This code is really old (from the time I added support for WinTV USB 2).
I suspect I added the sleep there just because the I2C logs, during the
driver development phase, to be an exact mimic on what it was got via
USB dumps.
-
- rc = i2c_master_recv(c, buffer, 1);
- if (rc < 0) {
- v4l2_err(sd, "i2c i/o error: rc == %d (should be 1)\n", rc);
- return rc;
+ rc = i2c_transfer(c->adapter, msg, 2);
+ if (rc < 0 || rc != 2) {
+ v4l2_err(sd, "i2c i/o error: rc == %d (should be 2)\n", rc);
+ return rc < 0 ? rc : -EIO;
}
v4l2_dbg(2, debug, sd, "tvp5150: read 0x%02x = 0x%02x\n", addr, buffer[0]);
Looks good and works without problems with my HVR-900 and WinTV 2
devices (both em28xx).
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