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linux/drivers/clocksource
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Ronald Wahl b3b5c27304 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 17:19:36 +00:00
..
acpi_pm.c clocksource: Verify HPET and PMTMR when TSC unverified 2023-02-02 14:23:02 -08:00
arc_timer.c clocksource/drivers/arc_timer: Eliminate redefined macro error 2021-10-16 22:15:01 +02:00
arm_arch_timer.c clocksource/drivers/arm_arch_timer: limit XGene-1 workaround 2023-11-20 11:59:12 +01:00
arm_global_timer.c clocksource/drivers/arm_global_timer: Remove duplicated argument in arm_global_timer 2021-06-16 17:33:04 +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 2019-11-04 10:40:10 +01:00
bcm2835_timer.c clocksource: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
bcm_kona_timer.c clocksource/drivers/bcm_kona: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
clksrc_st_lpc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
clksrc-dbx500-prcmu.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
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_of.c clocksource/drivers/dw_apb_timer_of: Fix probe failure 2021-12-10 17:46:54 +01:00
dw_apb_timer.c clocksource: dw_apb_timer: Make CPU-affiliation being optional 2020-05-23 00:02:41 +02:00
em_sti.c clocksource: remove MODULE_LICENSE in non-modules 2023-04-13 13:13:51 -07:00
exynos_mct.c clocksource/drivers/exynos_mct: Explicitly return 0 for shared timer 2023-04-24 16:56:13 +02:00
hyperv_timer.c clocksource: hyper-v: Mark hyperv tsc page unencrypted in sev-snp enlightened guest 2023-08-22 00:38:20 +00:00
i8253.c
ingenic-ost.c clocksource/drivers/ingenic-ost: Define pm functions properly in platform_driver struct 2022-12-01 11:56:36 +01:00
ingenic-sysost.c clocksource/drivers/ingenic: Use bitfield macro helpers 2021-08-14 02:44:35 +02:00
ingenic-timer.c clocksource/drivers/ingenic-timer: Use pm_sleep_ptr() macro 2023-06-19 16:17:42 +02:00
jcore-pit.c clocksource/drivers/jcore: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
Kconfig clocksource/drivers/timer-oxnas-rps: Remove obsolete timer driver 2023-07-13 14:46:17 +02:00
Makefile clocksource/drivers/timer-oxnas-rps: Remove obsolete timer driver 2023-07-13 14:46:17 +02:00
mips-gic-timer.c clocksource/drivers/mips-gic-timer: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
mmio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mps2-timer.c clocksource/drivers/mps2-timer: Use semicolons rather than commas to separate statements 2020-10-01 10:07:26 +02:00
mxs_timer.c clocksource/drivers/mxs_timer: Add missing semicolon when DEBUG is defined 2021-01-18 22:28:59 +01:00
nomadik-mtu.c clocksource: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
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: Add support for RZ/V2L SoC 2022-09-07 10:12:56 +02:00
samsung_pwm_timer.c clocksource/drivers/samsung_pwm: Constify source IO memory 2021-06-04 10:12:13 +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: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
sh_mtu2.c Timekeeping and clocksource/event driver updates the second batch: 2023-04-29 10:24:30 -07:00
sh_tmu.c clocksource: remove MODULE_LICENSE in non-modules 2023-04-13 13:13:51 -07:00
timer-armada-370-xp.c clocksource/drivers/armada-370-xp: Convert to SPDX identifier 2022-05-18 11:08:59 +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 clocksource/drivers/atmel-st: Remove useless 'status' 2020-04-15 10:57:15 +02:00
timer-atmel-tcb.c clocksource/drivers/timer-atmel-tcb: Fix initialization on SAM9 hardware 2023-11-28 17:19:36 +00:00
timer-cadence-ttc.c clocksource: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
timer-clint.c RISC-V: Allow marking IPIs as suitable for remote FENCEs 2023-04-08 11:26:24 +01:00
timer-cs5535.c clocksource/drivers/timer-cs5535: Request irq with non-NULL dev_id 2020-03-12 19:23:06 +01:00
timer-davinci.c clocksource/drivers/davinci: Fix memory leak in davinci_timer_register when init fails 2023-04-24 16:56:13 +02:00
timer-digicolor.c clocksource/drivers/digicolor: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
timer-fsl-ftm.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-fttmr010.c clocksource/drivers/fttmr010: Pass around less pointers 2021-08-14 10:49:49 +02:00
timer-goldfish.c clocksource/drivers: Add a goldfish-timer clocksource 2022-04-11 11:48:01 +02:00
timer-gx6605s.c clocksource/drivers/timer-gx6605s: Fixup counter reload 2020-08-24 13:01:39 +02:00
timer-gxp.c clocksource: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
timer-imx-gpt.c clocksource/drivers/timer-imx-gpt: Fix potential memory leak 2023-11-28 17:19:36 +00:00
timer-imx-sysctr.c clocksource/drivers/imx-sysctr: handle nxp,no-divider property 2022-09-20 10:49:46 +02:00
timer-imx-tpm.c clocksource/drivers/imx-tpm: Move tpm_read_sched_clock() under CONFIG_ARM 2022-03-07 18:27:22 +01:00
timer-integrator-ap.c clocksource: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
timer-ixp4xx.c clocksource/drivers/ixp4xx: Drop boardfile probe path 2022-05-18 11:08:52 +02:00
timer-keystone.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-loongson1-pwm.c clocksource/drivers/loongson1: Set variable ls1x_timer_lock storage-class-specifier to static 2023-08-18 12:13:03 +02:00
timer-lpc32xx.c clocksource/drivers/lpc32xx: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
timer-mediatek-cpux.c clocksource/drivers/timer-mediatek: Split out CPUXGPT timers 2023-04-24 16:56:13 +02:00
timer-mediatek.c clocksource/drivers/timer-mediatek: Split out CPUXGPT timers 2023-04-24 16:56:13 +02:00
timer-meson6.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-microchip-pit64b.c clocksource/drivers/timer-microchip-pit64b: Add delay timer 2023-02-13 13:10:17 +01:00
timer-milbeaut.c clocksource/drivers/timer-milbeaut: Cleanup common register accesses 2019-05-02 21:55:58 +02:00
timer-mp-csky.c
timer-msc313e.c clocksource/drivers/msc313e: Add support for ssd20xd-based platforms 2021-12-20 13:28:39 +01:00
timer-npcm7xx.c clocksource/drivers/timer-npcm7xx: Enable timer 1 clock before use 2022-12-02 12:48:28 +01:00
timer-of.c clocksource/drivers/timer-of: Check return value of of_iomap in timer_of_base_init() 2022-03-07 19:21:25 +01:00
timer-of.h
timer-orion.c clocksource/drivers/orion: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
timer-owl.c clocksource/drivers/owl: Improve owl_timer_init fail messages 2020-02-27 09:42:00 +01:00
timer-pistachio.c clocksource/drivers/pistachio: Convert to SPDX identifier 2022-05-18 11:08:59 +02:00
timer-probe.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
timer-pxa.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
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 clocksource/timer-riscv: Add ACPI support 2023-06-01 08:45:12 -07:00
timer-rockchip.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
timer-sp804.c clocksource/drivers/sp804: Do not use timer namespace for timer_shutdown() function 2022-11-24 15:09:10 +01:00
timer-sp.h clocksource/drivers/sp804: Enable Hisilicon sp804 timer 64bit mode 2020-09-24 10:51:04 +02:00
timer-sprd.c
timer-stm32-lp.c Timekeeping and clocksource/event driver updates the second batch: 2023-04-29 10:24:30 -07:00
timer-stm32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
timer-sun4i.c clocksource/drivers/timer-sun4i: Add CLOCK_EVT_FEAT_DYNIRQ 2023-02-13 13:10:17 +01:00
timer-sun5i.c clocksource/drivers/sun5i: Convert to platform device driver 2023-08-18 12:15:22 +02:00
timer-tegra186.c clocksource: Explicitly include correct DT includes 2023-08-28 13:30:57 -05:00
timer-tegra.c clocksource/drivers/tegra: Set up maximum-ticks limit properly 2019-06-25 19:49:18 +02:00
timer-ti-32k.c clocksource/drivers: Replace HTTP links with HTTPS ones 2020-07-23 16:57:43 +02:00
timer-ti-dm-systimer.c clocksource/drivers/ti: Use of_property_read_bool() for boolean properties 2023-04-24 16:56:14 +02:00
timer-ti-dm.c drivers/clocksource/timer-ti-dm: Don't call clk_get_rate() in stop function 2023-11-20 11:58:53 +01:00
timer-versatile.c clocksource/drivers/timer-versatile: Clear OF_POPULATED flag 2020-05-23 00:03:25 +02:00
timer-vf-pit.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
timer-vt8500.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00
timer-zevio.c clocksource: Replace setup_irq() by request_irq() 2020-02-27 12:15:24 +01:00