On Wed, Nov 21, 2012 at 1:08 PM, Olof Johansson <olof@xxxxxxxxx> wrote: > 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> Reviewed-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx> > > -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
