From dc8685b565d6526aca6aaefb80059d115c124821 Mon Sep 17 00:00:00 2001 From: Devin Heitmueller Date: Wed, 11 Mar 2009 03:00:56 -0300 Subject: [PATCH] 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 and Steven Toth for providing sample hardware, engineering level support, and testing. Signed-off-by: Devin Heitmueller Signed-off-by: Michael Krufky Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/au0828/au0828-i2c.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/media/video/au0828/au0828-i2c.c b/drivers/media/video/au0828/au0828-i2c.c index ee3e3040d54c..d57a38f5c738 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]); -- 2.20.1