android_kernel_motorola_sm6375/drivers/clocksource
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Ronald Wahl 91f7467ac9 clocksource/drivers/timer-atmel-tcb: Fix initialization on SAM9 hardware
[ Upstream commit 6d3bc4c02d59996d1d3180d8ed409a9d7d5900e0 ]

On SAM9 hardware two cascaded 16 bit timers are used to form a 32 bit
high resolution timer that is used as scheduler clock when the kernel
has been configured that way (CONFIG_ATMEL_CLOCKSOURCE_TCB).

The driver initially triggers a reset-to-zero of the two timers but this
reset is only performed on the next rising clock. For the first timer
this is ok - it will be in the next 60ns (16MHz clock). For the chained
second timer this will only happen after the first timer overflows, i.e.
after 2^16 clocks (~4ms with a 16MHz clock). So with other words the
scheduler clock resets to 0 after the first 2^16 clock cycles.

It looks like that the scheduler does not like this and behaves wrongly
over its lifetime, e.g. some tasks are scheduled with a long delay. Why
that is and if there are additional requirements for this behaviour has
not been further analysed.

There is a simple fix for resetting the second timer as well when the
first timer is reset and this is to set the ATMEL_TC_ASWTRG_SET bit in
the Channel Mode register (CMR) of the first timer. This will also rise
the TIOA line (clock input of the second timer) when a software trigger
respective SYNC is issued.

Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20231007161803.31342-1-rwahl@gmx.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-11-28 16:50:13 +00:00
..
acpi_pm.c
arc_timer.c
arm_arch_timer.c
arm_global_timer.c
armv7m_systick.c
asm9260_timer.c
bcm2835_timer.c
bcm_kona_timer.c
clksrc-dbx500-prcmu.c
clksrc_st_lpc.c
clps711x-timer.c
dummy_timer.c
dw_apb_timer.c
dw_apb_timer_of.c
em_sti.c
exynos_mct.c
h8300_timer8.c
h8300_timer16.c
h8300_tpu.c
hyperv_timer.c
i8253.c
ingenic-timer.c
jcore-pit.c
Kconfig
Makefile
mips-gic-timer.c
mmio.c
mps2-timer.c
mxs_timer.c
nomadik-mtu.c
numachip.c
renesas-ostm.c
samsung_pwm_timer.c
scx200_hrt.c
sh_cmt.c clocksource/drivers/sh_cmt: Make sure channel clock supply is enabled 2023-01-18 11:40:56 +01:00
sh_mtu2.c
sh_tmu.c
timer-armada-370-xp.c
timer-atcpit100.c
timer-atlas7.c
timer-atmel-pit.c
timer-atmel-st.c
timer-atmel-tcb.c clocksource/drivers/timer-atmel-tcb: Fix initialization on SAM9 hardware 2023-11-28 16:50:13 +00:00
timer-cadence-ttc.c clocksource/drivers/cadence-ttc: Fix memory leak in ttc_timer_probe 2023-07-27 08:37:05 +02:00
timer-cs5535.c
timer-davinci.c clocksource/drivers/davinci: Fix memory leak in davinci_timer_register when init fails 2023-05-17 11:35:53 +02:00
timer-digicolor.c
timer-efm32.c
timer-fsl-ftm.c
timer-fttmr010.c
timer-gx6605s.c
timer-imx-gpt.c clocksource/drivers/timer-imx-gpt: Fix potential memory leak 2023-11-28 16:50:13 +00:00
timer-imx-sysctr.c
timer-imx-tpm.c
timer-integrator-ap.c
timer-ixp4xx.c
timer-keystone.c
timer-lpc32xx.c
timer-mediatek.c
timer-meson6.c
timer-milbeaut.c
timer-mp-csky.c
timer-npcm7xx.c
timer-nps.c
timer-of.c
timer-of.h
timer-orion.c
timer-owl.c
timer-oxnas-rps.c
timer-pistachio.c
timer-prima2.c
timer-probe.c
timer-pxa.c
timer-qcom.c
timer-rda.c
timer-riscv.c Revert "clocksource/drivers/riscv: Events are stopped during CPU suspend" 2022-12-08 11:23:06 +01:00
timer-rockchip.c
timer-sp.h
timer-sp804.c
timer-sprd.c
timer-stm32.c
timer-sun4i.c
timer-sun5i.c
timer-tango-xtal.c
timer-tegra.c
timer-ti-32k.c
timer-ti-dm.c
timer-u300.c
timer-versatile.c
timer-vf-pit.c
timer-vt8500.c
timer-zevio.c