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authorDevin Heitmueller <dheitmueller@linuxtv.org>2009-03-11 03:00:56 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2009-03-30 12:43:26 -0300
commitdc8685b565d6526aca6aaefb80059d115c124821 (patch)
tree0e56cb018f4ace06cd7948b7ff2705e7deb22c52 /drivers/media/video
parent5a5a4e16fa19fa3789398e8c707168b7da718b64 (diff)
V4L/DVB (11074): au0828: fix i2c enumeration bug
There was a bug where enumerating the i2c for devices would result in false positives. The root of the issue was the scanning was using SMBUS_QUICK messages, which are zero length write requests (which our i2c adapter implementation didn't handle). Because we never strobed any bytes onto the bus, the status register would still contain the value from the previous request. Thanks to Michael Krufky <mkrufky@linuxtv.org> and Steven Toth <stoth@linuxtv.org> for providing sample hardware, engineering level support, and testing. Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org> Signed-off-by: Michael Krufky <mkrufky@linuxtv.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/video')
-rw-r--r--drivers/media/video/au0828/au0828-i2c.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/media/video/au0828/au0828-i2c.c b/drivers/media/video/au0828/au0828-i2c.c
index ee3e3040d54..d57a38f5c73 100644
--- a/drivers/media/video/au0828/au0828-i2c.c
+++ b/drivers/media/video/au0828/au0828-i2c.c
@@ -156,6 +156,24 @@ static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
dprintk(4, "SEND: %02x\n", msg->addr);
+ /* Deal with i2c_scan */
+ if (msg->len == 0) {
+ /* The analog tuner detection code makes use of the SMBUS_QUICK
+ message (which involves a zero length i2c write). To avoid
+ checking the status register when we didn't strobe out any
+ actual bytes to the bus, just do a read check. This is
+ consistent with how I saw i2c device checking done in the
+ USB trace of the Windows driver */
+ au0828_write(dev, REG_200, 0x20);
+ if (!i2c_wait_done(i2c_adap))
+ return -EIO;
+
+ if (i2c_wait_read_ack(i2c_adap))
+ return -EIO;
+
+ return 0;
+ }
+
for (i = 0; i < msg->len;) {
dprintk(4, " %02x\n", msg->buf[i]);