| Message ID | 1388232976-20061-12-git-send-email-mchehab@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Am 28.12.2013 13:16, schrieb Mauro Carvalho Chehab: > From: Mauro Carvalho Chehab <m.chehab@samsung.com> > > 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@samsung.com> > --- > 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. > + { .addr = c->addr, .flags = I2C_M_RD, > + .buf = buffer, .len = 1 } > + }; > > buffer[0] = addr; > > - 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. > - > - 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). -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Em Wed, 01 Jan 2014 19:52:08 +0100 Frank Schäfer <fschaefer.oss@googlemail.com> escreveu: > Am 28.12.2013 13:16, schrieb Mauro Carvalho Chehab: > > From: Mauro Carvalho Chehab <m.chehab@samsung.com> > > > > 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@samsung.com> > > --- > > 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. > > > + { .addr = c->addr, .flags = I2C_M_RD, > > + .buf = buffer, .len = 1 } > > + }; > > > > buffer[0] = addr; > > > > - 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). >
On 02.01.2014 20:20, Mauro Carvalho Chehab wrote: > Em Wed, 01 Jan 2014 19:52:08 +0100 > Frank Schäfer <fschaefer.oss@googlemail.com> escreveu: > >> Am 28.12.2013 13:16, schrieb Mauro Carvalho Chehab: >>> From: Mauro Carvalho Chehab <m.chehab@samsung.com> >>> >>> 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@samsung.com> >>> --- >>> 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). >> > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 }, + { .addr = c->addr, .flags = I2C_M_RD, + .buf = buffer, .len = 1 } + }; buffer[0] = addr; - 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); - - 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]);