On Tue, Nov 20, 2012 at 8:12 PM, Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > The changes in "i2c-s3c2410: use exponential back off while polling for > bus idle" remove the initial busy wait for I2C transfers to complete and > replace it with usleep_range() calls which will schedule. > > Since for older SoCs I2C transfers would usually complete within an > extremely small number of CPU cycles there is a win from not having to > schedule. This happens because on the older SoCs the cores run at a > smaller multiple of the speeds that the I2C bus is operating at; on more > modern SoCs the busy wait is less likely to be effective. > > Fix the issue by restoring the busy wait, reducing the number of spins > from 20 to 3 which covers the overwhelming majority of I2C transfers on > the SoCs where the busy wait is effective. > > Signed-off-by: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> Acked-by: Olof Johansson <olof@xxxxxxxxx> -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
