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| author | Jean Delvare <khali@linux-fr.org> | 2010-03-02 12:23:40 +0100 |
|---|---|---|
| committer | Jean Delvare <khali@linux-fr.org> | 2010-03-02 12:23:40 +0100 |
| commit | c05d490234b7cf1715d9568d2041d9bc598a0b45 (patch) | |
| tree | 6bc16bff57c044834563cc46a9528ceea54ad6f5 /drivers/i2c/busses/i2c-tiny-usb.c | |
| parent | 393764340beb595c1ad7dd2d2243c2b6551aaa71 (diff) | |
| download | blackbird-op-linux-c05d490234b7cf1715d9568d2041d9bc598a0b45.tar.gz blackbird-op-linux-c05d490234b7cf1715d9568d2041d9bc598a0b45.zip | |
i2c-tiny-usb: Fix a comment on bus frequency
The description of the delay parameter is incomplete, it suggests that
there is a direct relation between the delay value and the bus
frequency. In fact, due to additional delays in the i2c bitbanging
code, the i2c clock is always much slower.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Till Harbaum <Till@Harbaum.org>
Diffstat (limited to 'drivers/i2c/busses/i2c-tiny-usb.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-tiny-usb.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c index 41adb390e49c..b5b1bbf37d3c 100644 --- a/drivers/i2c/busses/i2c-tiny-usb.c +++ b/drivers/i2c/busses/i2c-tiny-usb.c @@ -31,11 +31,13 @@ #define CMD_I2C_IO_BEGIN (1<<0) #define CMD_I2C_IO_END (1<<1) -/* i2c bit delay, default is 10us -> 100kHz */ +/* i2c bit delay, default is 10us -> 100kHz max + (in practice, due to additional delays in the i2c bitbanging + code this results in a i2c clock of about 50kHz) */ static unsigned short delay = 10; module_param(delay, ushort, 0); -MODULE_PARM_DESC(delay, "bit delay in microseconds, " - "e.g. 10 for 100kHz (default is 100kHz)"); +MODULE_PARM_DESC(delay, "bit delay in microseconds " + "(default is 10us for 100kHz max)"); static int usb_read(struct i2c_adapter *adapter, int cmd, int value, int index, void *data, int len); |
