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| author | Trent Piepho <xyzzy@speakeasy.org> | 2007-03-12 16:13:12 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@infradead.org> | 2007-04-27 20:44:43 +0200 |
| commit | 57f8dcf90bdf4c6b23ea2af3d307d1d137b696b9 (patch) | |
| tree | 75ca4bd18c877bdf08164d806c9f235eee64f2ef /drivers/media/dvb/dvb-usb/m920x.c | |
| parent | V4L/DVB (5427): M920x: Improve I2C operations (diff) | |
| download | linux-57f8dcf90bdf4c6b23ea2af3d307d1d137b696b9.tar.xz linux-57f8dcf90bdf4c6b23ea2af3d307d1d137b696b9.zip | |
V4L/DVB (5428): M920x: Detect zero-length I2C messages and fix a typo
Change a 00 to just 0
Detect zero-length I2C messages and return not supported. I think I know
how to send one, but the problem is getting the slave's ack. The only
point of a zero-length message is for probing; too see if the slave will
ack its address. Since we don't know how to get the ack, we can't
support zero-length messages in a useful way, so it's probably best to
just return not supported for them.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Diffstat (limited to 'drivers/media/dvb/dvb-usb/m920x.c')
| -rw-r--r-- | drivers/media/dvb/dvb-usb/m920x.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/media/dvb/dvb-usb/m920x.c b/drivers/media/dvb/dvb-usb/m920x.c index 08469ccabb72..8c954814f827 100644 --- a/drivers/media/dvb/dvb-usb/m920x.c +++ b/drivers/media/dvb/dvb-usb/m920x.c @@ -148,13 +148,18 @@ static int m9206_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], return -EAGAIN; for (i = 0; i < num; i++) { - if (msg[i].flags & (I2C_M_NO_RD_ACK|I2C_M_IGNORE_NAK|I2C_M_TEN)) { + if (msg[i].flags & (I2C_M_NO_RD_ACK|I2C_M_IGNORE_NAK|I2C_M_TEN) || + msg[i].len == 0) { + /* For a 0 byte message, I think sending the address to index 0x80|0x40 + * would be the correct thing to do. However, zero byte messages are + * only used for probing, and since we don't know how to get the slave's + * ack, we can't probe. */ ret = -ENOTSUPP; goto unlock; } /* Send START & address/RW bit */ if (!(msg[i].flags & I2C_M_NOSTART)) { - if ((ret = m9206_write(d->udev, M9206_I2C, (msg[i].addr<<1)|(msg[i].flags&I2C_M_RD?0x01:00), 0x80)) != 0) + if ((ret = m9206_write(d->udev, M9206_I2C, (msg[i].addr<<1)|(msg[i].flags&I2C_M_RD?0x01:0), 0x80)) != 0) goto unlock; /* Should check for ack here, if we knew how. */ } |