From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Nicolas Pitre <nico@linaro.org>,
Russell King <rmk+kernel@armlinux.org.uk>
Subject: [PATCH 4.8 29/37] ARM: fix delays
Date: Fri, 14 Oct 2016 14:27:15 +0200 [thread overview]
Message-ID: <20161014122553.988073773@linuxfoundation.org> (raw)
In-Reply-To: <20161014122549.411962735@linuxfoundation.org>
4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Russell King <rmk+kernel@armlinux.org.uk>
commit fb833b1fbb68461772dbf5e91bddea5e839187e9 upstream.
Commit 215e362dafed ("ARM: 8306/1: loop_udelay: remove bogomips value
limitation") tried to increase the bogomips limitation, but in doing
so messed up udelay such that it always gives about a 5% error in the
delay, even if we use a timer.
The calculation is:
loops = UDELAY_MULT * us_delay * ticks_per_jiffy >> UDELAY_SHIFT
Originally, UDELAY_MULT was ((UL(2199023) * HZ) >> 11) and UDELAY_SHIFT
30. Assuming HZ=100, us_delay of 1000 and ticks_per_jiffy of 1660000
(eg, 166MHz timer, 1ms delay) this would calculate:
((UL(2199023) * HZ) >> 11) * 1000 * 1660000 >> 30
=> 165999
With the new values of 2047 * HZ + 483648 * HZ / 1000000 and 31, we get:
(2047 * HZ + 483648 * HZ / 1000000) * 1000 * 1660000 >> 31
=> 158269
which is incorrect. This is due to a typo - correcting it gives:
(2147 * HZ + 483648 * HZ / 1000000) * 1000 * 1660000 >> 31
=> 165999
i.o.w, the original value.
Fixes: 215e362dafed ("ARM: 8306/1: loop_udelay: remove bogomips value limitation")
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/include/asm/delay.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm/include/asm/delay.h
+++ b/arch/arm/include/asm/delay.h
@@ -10,7 +10,7 @@
#include <asm/param.h> /* HZ */
#define MAX_UDELAY_MS 2
-#define UDELAY_MULT UL(2047 * HZ + 483648 * HZ / 1000000)
+#define UDELAY_MULT UL(2147 * HZ + 483648 * HZ / 1000000)
#define UDELAY_SHIFT 31
#ifndef __ASSEMBLY__
next prev parent reply other threads:[~2016-10-14 12:29 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20161014122720uscas1p185a2db67245495161c918bca0cd90f23@uscas1p1.samsung.com>
2016-10-14 12:26 ` [PATCH 4.8 00/37] 4.8.2-stable review Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 01/37] usb: storage: fix runtime pm issue in usb_stor_probe2 Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 02/37] timekeeping: Fix __ktime_get_fast_ns() regression Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 03/37] usb: dwc3: fix Clear Stall EP command failure Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 04/37] phy: sun4i-usb: Use spinlock to guard phyctl register access Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 05/37] ALSA: ali5451: Fix out-of-bound position reporting Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 06/37] ALSA: usb-audio: Extend DragonFly dB scale quirk to cover other variants Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 07/37] ALSA: usb-line6: use the same declaration as definition in header for MIDI manufacturer ID Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 08/37] mfd: rtsx_usb: Avoid setting ucr->current_sg.status Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 09/37] mfd: atmel-hlcdc: Do not sleep in atomic context Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 10/37] mfd: 88pm80x: Double shifting bug in suspend/resume Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 12/37] xen/x86: Update topology map for PV VCPUs Greg Kroah-Hartman
2016-10-14 12:26 ` [PATCH 4.8 13/37] KVM: PPC: Book3s PR: Allow access to unprivileged MMCR2 register Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 14/37] KVM: MIPS: Drop other CPU ASIDs on guest MMU changes Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 15/37] KVM: arm64: Require in-kernel irqchip for PMU support Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 16/37] KVM: arm/arm64: vgic: Dont flush/sync without a working vgic Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 17/37] KVM: PPC: BookE: Fix a sanity check Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 18/37] arm64: fix dump_backtrace/unwind_frame with NULL tsk Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 19/37] x86/boot: Fix kdump, cleanup aborted E820_PRAM max_pfn manipulation Greg Kroah-Hartman
2016-10-14 12:27 ` Greg Kroah-Hartman
2016-10-14 12:27 ` Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 20/37] x86/irq: Prevent force migration of irqs which are not in the vector domain Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 21/37] x86/pkeys: Make protection keys an "eager" feature Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 22/37] x86/cpu: Rename Merrifield2 to Moorefield Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 23/37] x86/platform/intel-mid: Add Intel Penwell to ID table Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 24/37] x86/platform/intel-mid: Keep SRAM powered on at boot Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 25/37] x86/apic: Get rid of apic_version[] array Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 26/37] arch/x86: Handle non enumerated CPU after physical hotplug Greg Kroah-Hartman
2016-10-14 12:27 ` Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 27/37] x86/mm/pkeys: Do not skip PKRU register if debug registers are not used Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 28/37] x86/dumpstack: Fix x86_32 kernel_stack_pointer() previous stack access Greg Kroah-Hartman
2016-10-14 12:27 ` Greg Kroah-Hartman [this message]
2016-10-14 12:27 ` [PATCH 4.8 30/37] ARM: dts: mvebu: armada-390: add missing compatibility string and bracket Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 33/37] ARM: cpuidle: Fix error return code Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 34/37] Bluetooth: Add a new 04ca:3011 QCA_ROME device Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 35/37] ima: use file_dentry() Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 36/37] tpm: fix a race condition in tpm2_unseal_trusted() Greg Kroah-Hartman
2016-10-14 12:27 ` [PATCH 4.8 37/37] tpm_crb: fix crb_req_canceled behavior Greg Kroah-Hartman
2016-10-14 18:53 ` [PATCH 4.8 00/37] 4.8.2-stable review Shuah Khan
2016-10-15 11:50 ` Greg Kroah-Hartman
2016-10-14 19:16 ` Guenter Roeck
2016-10-15 11:51 ` Greg Kroah-Hartman
[not found] ` <58013af0.6106c30a.958bb.adf8@mx.google.com>
2016-10-15 11:38 ` Greg Kroah-Hartman
2016-10-17 16:43 ` Kevin Hilman
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