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linux-stable/drivers/clocksource
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Ronald Wahl 91f7467ac9 clocksource/drivers/timer-atmel-tcb: Fix initialization on SAM9 hardware 
[ Upstream commit 6d3bc4c02d ]

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 clocksource: acpi_pm: fix return value of __setup handler 2022-04-15 14:18:05 +02:00
arc_timer.c Merge branch 'timers/vdso' into timers/core 2019-07-03 10:50:21 +02:00
arm_arch_timer.c clocksource/arm_arch_timer: Improve Allwinner A64 timer workaround 2021-07-19 08:53:15 +02:00
arm_global_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
armv7m_systick.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
asm9260_timer.c clocksource/drivers/asm9260: Add a check for of_clk_get 2020-01-04 19:17:07 +01:00
bcm2835_timer.c clocksource/drivers/bcm2835_timer: Fix memory leak of timer 2020-02-24 08:36:28 +01:00
bcm_kona_timer.c
clksrc-dbx500-prcmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 197 2019-05-30 11:29:22 -07:00
clksrc_st_lpc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
clps711x-timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
dummy_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
dw_apb_timer.c clocksource: dw_apb_timer: Make CPU-affiliation being optional 2020-06-22 09:30:55 +02:00
dw_apb_timer_of.c clocksource: dw_apb_timer_of: Fix missing clockevent timers 2020-06-22 09:30:55 +02:00
em_sti.c clocksource: Remove dev_err() usage after platform_get_irq() 2019-08-27 00:31:39 +02:00
exynos_mct.c Merge branch 'timers/vdso' into timers/core 2019-07-03 10:50:21 +02:00
h8300_timer8.c clocksource/drivers/h8300_timer8: Fix wrong return value in h8300_8timer_init() 2020-10-01 13:18:16 +02:00
h8300_timer16.c
h8300_tpu.c
hyperv_timer.c clocksource: hyper-v: unexport __init-annotated hv_init_clocksource() 2022-06-22 14:11:21 +02:00
i8253.c
ingenic-timer.c clocksource: Add a new timer-ingenic driver 2019-08-08 15:30:08 -07:00
jcore-pit.c
Kconfig clocksource/drivers/timer-ti-dm: Select TIMER_OF 2021-11-17 09:48:39 +01:00
Makefile clocksource: Add a new timer-ingenic driver 2019-08-08 15:30:08 -07:00
mips-gic-timer.c clocksource/drivers/mips-gic-timer: Make gic_compare_irqaction static 2019-03-22 22:59:33 +01:00
mmio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mps2-timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mxs_timer.c clocksource/drivers/mxs_timer: Add missing semicolon when DEBUG is defined 2021-03-04 10:26:29 +01:00
nomadik-mtu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
numachip.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
renesas-ostm.c clocksource/drivers/renesas-ostm: Use DIV_ROUND_CLOSEST() helper 2019-08-27 00:31:39 +02:00
samsung_pwm_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
scx200_hrt.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
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 clocksource/drivers/sh_mtu2: Do not loop using platform_get_irq_by_name() 2019-10-18 07:55:16 +02:00
sh_tmu.c clocksource: Remove dev_err() usage after platform_get_irq() 2019-08-27 00:31:39 +02:00
timer-armada-370-xp.c
timer-atcpit100.c
timer-atlas7.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 4 2019-05-21 11:28:40 +02:00
timer-atmel-pit.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-atmel-st.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-fsl-ftm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
timer-fttmr010.c
timer-gx6605s.c clocksource/drivers/timer-gx6605s: Fixup counter reload 2020-10-07 08:01:25 +02:00
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 clocksource/drivers/imx-sysctr: Add internal clock divider handle 2019-08-27 00:31:39 +02:00
timer-imx-tpm.c
timer-integrator-ap.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
timer-ixp4xx.c clocksource/drivers/ixp4xx: remove EXPORT_SYMBOL_GPL from ixp4xx_timer_setup() 2022-07-07 17:36:53 +02:00
timer-keystone.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-lpc32xx.c
timer-mediatek.c clocksource/drivers/mediatek: Fix error handling 2019-10-16 17:04:50 +02:00
timer-meson6.c clocksource/drivers/timer-meson6: Update with SPDX Licence identifier 2019-06-25 19:49:18 +02:00
timer-milbeaut.c clocksource/drivers/timer-milbeaut: Cleanup common register accesses 2019-05-02 21:55:58 +02:00
timer-mp-csky.c
timer-npcm7xx.c clocksource/drivers/npcm: Fix GENMASK and timer operation 2019-08-27 00:31:39 +02:00
timer-nps.c
timer-of.c clocksource/drivers/timer-of: Check return value of of_iomap in timer_of_base_init() 2022-04-15 14:18:05 +02:00
timer-of.h
timer-orion.c clocksource/drivers/orion: Add missing clk_disable_unprepare() on error path 2020-12-30 11:51:17 +01:00
timer-owl.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
timer-oxnas-rps.c clocksource/drivers/oxnas-rps: Fix irq_of_parse_and_map() return value 2022-06-14 18:11:54 +02:00
timer-pistachio.c
timer-prima2.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 4 2019-05-21 11:28:40 +02:00
timer-probe.c clocksource/drivers: Do not warn on probe defer 2019-08-27 00:31:39 +02:00
timer-pxa.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-qcom.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-sp.h
timer-sp804.c clocksource/drivers/sp804: Avoid error on multiple instances 2022-06-14 18:12:00 +02:00
timer-sprd.c
timer-stm32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
timer-sun4i.c clocksource: sun4i: Add missing compatibles 2019-08-27 00:31:39 +02:00
timer-sun5i.c clocksource/drivers/sun5i: Fail gracefully when clock rate is unavailable 2019-02-23 12:13:45 +01:00
timer-tango-xtal.c
timer-tegra.c clocksource/drivers/tegra: Set up maximum-ticks limit properly 2019-06-25 19:49:18 +02:00
timer-ti-32k.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 341 2019-06-05 17:37:07 +02:00
timer-ti-dm.c clocksource/drivers/timer-ti-dm: Change to new style declaration 2019-05-24 15:51:30 +02:00
timer-u300.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
timer-versatile.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
timer-vf-pit.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
timer-vt8500.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
timer-zevio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00