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>
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
index 41adb39..b5b1bbf 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);