kernel_optimize_test/drivers/i2c
Aaro Koskinen baf46b4e37 i2c: OMAP2/3: Fix scll/sclh calculations
Fix scll/sclh calculations for HS and fast modes. Currently the driver
uses equal (roughly) low/high times which will result in too short
low time.

OMAP3430 TRM gives the following equations:

	F/S: tLow  = (scll + 7) * internal_clk
	     tHigh = (sclh + 5) * internal_clk
	HS:  tLow  = (scll + 7) * fclk
	     tHigh = (sclh + 5) * fclk

Furthermore, the I2C specification sets the following minimum values
for HS tLow/tHigh for capacitive bus loads 100 pF (maximum speed 3400)
and 400 pF (maximum speed 1700):

	speed	tLow		tHigh
	3400	160 ns		60 ns
	1700	320 ns		120 ns

and for F/S:

	speed	tLow		tHigh
	400	1300 ns		600 ns
	100	4700 ns		4000 ns

By using duty cycles 33/66 (HS, F) and 50/50 (S) we stay above these
minimum values.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2009-06-13 10:39:25 +01:00
..
algos i2c-algo-pca: Let PCA9564 recover from unacked data byte (state 0x30) 2009-05-05 08:39:25 +02:00
busses i2c: OMAP2/3: Fix scll/sclh calculations 2009-06-13 10:39:25 +01:00
chips Move the pcf8591 driver to hwmon 2009-03-30 21:46:43 +02:00
i2c-boardinfo.c i2c: Add i2c_board_info and i2c_new_device() 2007-05-01 23:26:31 +02:00
i2c-core.c i2c: Let new-style drivers implement attach_adapter 2009-04-13 17:02:14 +02:00
i2c-core.h i2c: Add i2c_board_info and i2c_new_device() 2007-05-01 23:26:31 +02:00
i2c-dev.c i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT 2009-02-24 19:19:49 +01:00
Kconfig i2c: Let users select algorithm drivers manually again 2008-08-10 22:56:15 +02:00
Makefile i2c: Add i2c_board_info and i2c_new_device() 2007-05-01 23:26:31 +02:00