android_kernel_xiaomi_sm8450

xiaomi-sm8450/android_kernel_xiaomi_sm8450

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Oleksij Rempel 2b899f34e1 i2c: imx: reduce load by using usleep_range instead of udelay

Documentation/timers/timers-howto.txt recommends to use
usleep_range on delays > 10usec. According to my test results
with Neonode zForce touchscreen driver, usleep_range indeed
reduces CPU load.

Stats collected with "./perf record -a -g -F 1000 sleep 10"

i2c-imx with udelay(50):
34.19% 0.00% irq/220-Neonode [kernel.kallsyms] [k] irq_thread
    ---irq_thread
       |--33.75%--irq_thread_fn
       |    |--19.27%--0x7f08a878
       |    |     i2c_master_recv
       |    |     i2c_transfer
       |    |     __i2c_transfer
       |    |     i2c_imx_xfer
       |    |     |--11.71%--i2c_imx_trx_complete
       |    |     |--5.70%--i2c_imx_start <<<<----------------
       |    |     |     |--5.38%--__timer_const_udelay
       |    |     |     |      __timer_delay
       |    |     |     |      --5.07%--read_current_timer

i2c-imx with usleep_range(50,100)
29.08% 0.00% irq/220-Neonode  [kernel.kallsyms] [k] irq_thread
    ---irq_thread
       |--28.89%--irq_thread_fn
       |    |--17.21%--0x7f08a878
       |    |     i2c_master_recv
       |    |     |--17.14%--i2c_transfer
       |    |     |     __i2c_transfer
       |    |     |     i2c_imx_xfer
       |    |     |     |--14.29%--i2c_imx_trx_complete
       |    |     |     |--1.42%--i2c_imx_start <<<<----------
       |    |     |     |      |--0.71%--usleep_range
       |    |     |     |      |--0.53%--i2c_imx_bus_busy

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Reviewed-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2016-04-26 23:34:09 +02:00

algos

i2c: algo-bit: add I2C_AQ_NO_CLK_STRETCH

2015-11-30 18:37:25 +01:00

busses

i2c: imx: reduce load by using usleep_range instead of udelay

2016-04-26 23:34:09 +02:00

muxes

i2c: mux: pinctrl: fix indentation for better readability

2016-04-24 23:11:41 +02:00

i2c-boardinfo.c

i2c: i2c-boardinfo: sort includes