From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Tao Ren <taoren@fb.com>,
Linus Walleij <linus.walleij@linaro.org>,
Lei YU <mine260309@gmail.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.14 25/41] clocksource/drivers/fttmr010: Fix set_next_event handler
Date: Thu, 18 Oct 2018 19:54:40 +0200 [thread overview]
Message-ID: <20181018175421.419733800@linuxfoundation.org> (raw)
In-Reply-To: <20181018175416.718399607@linuxfoundation.org>
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tao Ren <taoren@fb.com>
[ Upstream commit 4451d3f59f2a6f95e5d205c2d04ea072955d080d ]
Currently, the aspeed MATCH1 register is updated to <current_count -
cycles> in set_next_event handler, with the assumption that COUNT
register value is preserved when the timer is disabled and it continues
decrementing after the timer is enabled. But the assumption is wrong:
RELOAD register is loaded into COUNT register when the aspeed timer is
enabled, which means the next event may be delayed because timer
interrupt won't be generated until <0xFFFFFFFF - current_count +
cycles>.
The problem can be fixed by updating RELOAD register to <cycles>, and
COUNT register will be re-loaded when the timer is enabled and interrupt
is generated when COUNT register overflows.
The test result on Facebook Backpack-CMM BMC hardware (AST2500) shows
the issue is fixed: without the patch, usleep(100) suspends the process
for several milliseconds (and sometimes even over 40 milliseconds);
after applying the fix, usleep(100) takes averagely 240 microseconds to
return under the same workload level.
Signed-off-by: Tao Ren <taoren@fb.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Lei YU <mine260309@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/clocksource/timer-fttmr010.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
--- a/drivers/clocksource/timer-fttmr010.c
+++ b/drivers/clocksource/timer-fttmr010.c
@@ -130,13 +130,17 @@ static int fttmr010_timer_set_next_event
cr &= ~fttmr010->t1_enable_val;
writel(cr, fttmr010->base + TIMER_CR);
- /* Setup the match register forward/backward in time */
- cr = readl(fttmr010->base + TIMER1_COUNT);
- if (fttmr010->count_down)
- cr -= cycles;
- else
- cr += cycles;
- writel(cr, fttmr010->base + TIMER1_MATCH1);
+ if (fttmr010->count_down) {
+ /*
+ * ASPEED Timer Controller will load TIMER1_LOAD register
+ * into TIMER1_COUNT register when the timer is re-enabled.
+ */
+ writel(cycles, fttmr010->base + TIMER1_LOAD);
+ } else {
+ /* Setup the match register forward in time */
+ cr = readl(fttmr010->base + TIMER1_COUNT);
+ writel(cr + cycles, fttmr010->base + TIMER1_MATCH1);
+ }
/* Start */
cr = readl(fttmr010->base + TIMER_CR);
next prev parent reply other threads:[~2018-10-18 18:00 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-18 17:54 [PATCH 4.14 00/41] 4.14.78-stable review Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 01/41] media: af9035: prevent buffer overflow on write Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 02/41] batman-adv: Avoid probe ELP information leak Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 03/41] batman-adv: Fix segfault when writing to throughput_override Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 04/41] batman-adv: Fix segfault when writing to sysfs elp_interval Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 05/41] batman-adv: Prevent duplicated gateway_node entry Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 06/41] batman-adv: Prevent duplicated nc_node entry Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 07/41] batman-adv: Prevent duplicated softif_vlan entry Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 08/41] batman-adv: Prevent duplicated global TT entry Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 09/41] batman-adv: Prevent duplicated tvlv handler Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 10/41] batman-adv: fix backbone_gw refcount on queue_work() failure Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 11/41] batman-adv: fix hardif_neigh " Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 12/41] clocksource/drivers/ti-32k: Add CLOCK_SOURCE_SUSPEND_NONSTOP flag for non-am43 SoCs Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 13/41] scsi: ibmvscsis: Fix a stringop-overflow warning Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 14/41] scsi: ibmvscsis: Ensure partition name is properly NUL terminated Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 15/41] intel_th: pci: Add Ice Lake PCH support Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 16/41] Input: atakbd - fix Atari keymap Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 17/41] Input: atakbd - fix Atari CapsLock behaviour Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 18/41] net: emac: fix fixed-link setup for the RTL8363SB switch Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 19/41] ravb: do not write 1 to reserved bits Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 20/41] PCI: dwc: Fix scheduling while atomic issues Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 21/41] drm: mali-dp: Call drm_crtc_vblank_reset on device init Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 22/41] scsi: ipr: System hung while dlpar adding primary ipr adapter back Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 23/41] scsi: sd: dont crash the host on invalid commands Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 24/41] net/mlx4: Use cpumask_available for eq->affinity_mask Greg Kroah-Hartman
2018-10-18 17:54 ` Greg Kroah-Hartman [this message]
2018-10-18 17:54 ` [PATCH 4.14 26/41] RISC-V: include linux/ftrace.h in asm-prototypes.h Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 27/41] powerpc/tm: Fix userspace r13 corruption Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 28/41] powerpc/tm: Avoid possible userspace r1 corruption on reclaim Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 29/41] iommu/amd: Return devid as alias for ACPI HID devices Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 30/41] powerpc/lib/feature-fixups: use raw_patch_instruction() Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 31/41] Revert "vfs: fix freeze protection in mnt_want_write_file() for overlayfs" Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 32/41] mremap: properly flush TLB before releasing the page Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 33/41] ARC: build: Get rid of toolchain check Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 34/41] ARC: build: Dont set CROSS_COMPILE in archs Makefile Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 35/41] HID: quirks: fix support for Apple Magic Keyboards Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 36/41] drm/i915: Nuke the LVDS lid notifier Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 37/41] staging: ccree: check DMA pool buf !NULL before free Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 38/41] mm: disallow mappings that conflict for devm_memremap_pages() Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 39/41] drm/i915/glk: Add Quirk for GLK NUC HDMI port issues Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 40/41] i2c: rcar: handle RXDMA HW behaviour on Gen3 Greg Kroah-Hartman
2018-10-18 17:54 ` [PATCH 4.14 41/41] IB/hfi1: Fix destroy_qp hang after a link down Greg Kroah-Hartman
2018-10-19 1:41 ` [PATCH 4.14 00/41] 4.14.78-stable review Nathan Chancellor
2018-10-19 8:15 ` Greg Kroah-Hartman
2018-10-19 12:10 ` Rafael David Tinoco
2018-10-19 15:49 ` Guenter Roeck
2018-10-19 20:43 ` Shuah Khan
2018-10-22 13:03 ` Jon Hunter
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