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From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>,
	Tony Lindgren <tony@atomide.com>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 3.18 22/98] ARM: dra7xx: Fix counter frequency drift for AM572x errata i856
Date: Thu, 25 Oct 2018 10:17:37 -0400	[thread overview]
Message-ID: <20181025141853.214051-22-sashal@kernel.org> (raw)
In-Reply-To: <20181025141853.214051-1-sashal@kernel.org>

From: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>

[ Upstream commit afc9d590b8a150cfeaac0078ef5de6fb21a5ea6a ]

Errata i856 for the AM572x (DRA7xx) points out that the 32.768KHz external
crystal is not enabled at power up.  Instead the CPU falls back to using
an emulation for the 32KHz clock which is SYSCLK1/610.  SYSCLK1 is usually
20MHz on boards so far (which gives an emulated frequency of 32.786KHz),
but can also be 19.2 or 27MHz which result in much larger drift.

Since this is used to drive the master counter at 32.768KHz * 375 /
2 = 6.144MHz, the emulated speed for 20MHz is of by 570ppm, or about 43
seconds per day, and more than the 500ppm NTP is able to tolerate.

Checking the CTRL_CORE_BOOTSTRAP register can determine if the CPU
is using the real 32.768KHz crystal or the emulated SYSCLK1/610, and
by known that the real counter frequency can be determined and used.
The real speed is then SYSCLK1 / 610 * 375 / 2 or SYSCLK1 * 75 / 244.

Signed-off-by: Len Sorensen <lsorense@csclub.uwaterloo.ca>
Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm/mach-omap2/control.h |  4 ++++
 arch/arm/mach-omap2/timer.c   | 36 +++++++++++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/control.h b/arch/arm/mach-omap2/control.h
index a3c013345c45..a80ac2d70bb1 100644
--- a/arch/arm/mach-omap2/control.h
+++ b/arch/arm/mach-omap2/control.h
@@ -286,6 +286,10 @@
 #define OMAP5XXX_CONTROL_STATUS                0x134
 #define OMAP5_DEVICETYPE_MASK          (0x7 << 6)
 
+/* DRA7XX CONTROL CORE BOOTSTRAP */
+#define DRA7_CTRL_CORE_BOOTSTRAP	0x6c4
+#define DRA7_SPEEDSELECT_MASK		(0x3 << 8)
+
 /*
  * REVISIT: This list of registers is not comprehensive - there are more
  * that should be added.
diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
index fb0cb2b817a9..7d45c84c69ba 100644
--- a/arch/arm/mach-omap2/timer.c
+++ b/arch/arm/mach-omap2/timer.c
@@ -54,6 +54,7 @@
 
 #include "soc.h"
 #include "common.h"
+#include "control.h"
 #include "powerdomain.h"
 #include "omap-secure.h"
 
@@ -496,7 +497,8 @@ static void __init realtime_counter_init(void)
 	void __iomem *base;
 	static struct clk *sys_clk;
 	unsigned long rate;
-	unsigned int reg, num, den;
+	unsigned int reg;
+	unsigned long long num, den;
 
 	base = ioremap(REALTIME_COUNTER_BASE, SZ_32);
 	if (!base) {
@@ -511,6 +513,35 @@ static void __init realtime_counter_init(void)
 	}
 
 	rate = clk_get_rate(sys_clk);
+
+	if (soc_is_dra7xx()) {
+		/*
+		 * Errata i856 says the 32.768KHz crystal does not start at
+		 * power on, so the CPU falls back to an emulated 32KHz clock
+		 * based on sysclk / 610 instead. This causes the master counter
+		 * frequency to not be 6.144MHz but at sysclk / 610 * 375 / 2
+		 * (OR sysclk * 75 / 244)
+		 *
+		 * This affects at least the DRA7/AM572x 1.0, 1.1 revisions.
+		 * Of course any board built without a populated 32.768KHz
+		 * crystal would also need this fix even if the CPU is fixed
+		 * later.
+		 *
+		 * Either case can be detected by using the two speedselect bits
+		 * If they are not 0, then the 32.768KHz clock driving the
+		 * coarse counter that corrects the fine counter every time it
+		 * ticks is actually rate/610 rather than 32.768KHz and we
+		 * should compensate to avoid the 570ppm (at 20MHz, much worse
+		 * at other rates) too fast system time.
+		 */
+		reg = omap_ctrl_readl(DRA7_CTRL_CORE_BOOTSTRAP);
+		if (reg & DRA7_SPEEDSELECT_MASK) {
+			num = 75;
+			den = 244;
+			goto sysclk1_based;
+		}
+	}
+
 	/* Numerator/denumerator values refer TRM Realtime Counter section */
 	switch (rate) {
 	case 12000000:
@@ -545,6 +576,7 @@ static void __init realtime_counter_init(void)
 		break;
 	}
 
+sysclk1_based:
 	/* Program numerator and denumerator registers */
 	reg = readl_relaxed(base + INCREMENTER_NUMERATOR_OFFSET) &
 			NUMERATOR_DENUMERATOR_MASK;
@@ -556,7 +588,7 @@ static void __init realtime_counter_init(void)
 	reg |= den;
 	writel_relaxed(reg, base + INCREMENTER_DENUMERATOR_RELOAD_OFFSET);
 
-	arch_timer_freq = (rate / den) * num;
+	arch_timer_freq = DIV_ROUND_UP_ULL(rate * num, den);
 	set_cntfreq();
 
 	iounmap(base);
-- 
2.17.1


  parent reply	other threads:[~2018-10-25 14:19 UTC|newest]

Thread overview: 107+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-25 14:17 [PATCH AUTOSEL 3.18 01/98] dm thin: restore requested 'error_if_no_space' setting on OODS to WRITE transition Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 02/98] ocfs2: fix journal commit deadlock in ocfs2_convert_inline_data_to_extents Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 03/98] s390/kvm: REPLACE barrier fixup with READ_ONCE Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 04/98] USB: qcserial: Fix support for HP lt4112 LTE/HSPA+ Gobi 4G Modem Sasha Levin
2018-10-26  8:49   ` Johan Hovold
2018-10-26  9:02     ` Bjørn Mork
2018-10-26  9:11       ` Johan Hovold
2018-10-26 10:59     ` Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 05/98] cxl: Fix issues when unmapping contexts Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 06/98] s390/ftrace/jprobes: Fix conflict between jprobes and function graph tracing Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 07/98] mmc: sdhci: restore behavior when setting VDD via external regulator Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 08/98] ARM: OMAP5 / DRA7: Fix HYP mode boot for thumb2 build Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 09/98] usb: gadget: gadgetfs: fix an oops in ep_write() Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 10/98] ahci_xgene: Fix the DMA state machine lockup for the ATA_CMD_PACKET PIO mode command Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 11/98] Revert "drm/i915: Fix mutex->owner inspection race under DEBUG_MUTEXES" Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 12/98] pinctrl: at91: fix null pointer dereference Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 13/98] PCI: Mark Atheros AR9580 to avoid bus reset Sasha Levin
2018-10-25 20:33   ` Tom Psyborg
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 14/98] ARM: shmobile: r8a7740: Instantiate GIC from C board code in legacy builds Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 15/98] usb: musb: Fix a few off-by-one lengths Sasha Levin
2018-10-26 10:47   ` Rasmus Villemoes
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 16/98] usb: gadget: f_uac1: access freed memory at f_audio_free_inst Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 17/98] usb: musb: Fix randconfig build issues for Kconfig options Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 18/98] usb: dwc2: gadget: kill requests with 'force' in s3c_hsotg_udc_stop() Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 19/98] phy-sun4i-usb: Change disconnect threshold value for sun6i Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 20/98] phy: phy-ti-pipe3: fix inconsistent enumeration of PCIe gen2 cards Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 21/98] iio: iio: Fix iio_channel_read return if channel havn't info Sasha Levin
2018-10-25 14:17 ` Sasha Levin [this message]
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 23/98] ARM: OMAP2+: Fix n900 board name for legacy user space Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 24/98] NFSv4: Cache the NFSv4/v4.1 client owner_id in the struct nfs_client Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 25/98] NFSv4/v4.1: Verify the client owner id during trunking detection Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 26/98] NFS: Ignore transport protocol when detecting server trunking Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 27/98] NFSv4: Remove incorrect check in can_open_delegated() Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 28/98] arm: dts: Use pmu_system_controller phandle for dp phy Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 29/98] scsi: ->queue_rq can't sleep Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 30/98] USB: EHCI: adjust error return code Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 31/98] uas: disable UAS on Apricorn SATA dongles Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 32/98] usb: host: ehci-tegra: request deferred probe when failing to get phy Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 33/98] Revert "tty: Fix pty master poll() after slave closes v2" Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 34/98] serial: samsung: Add the support for Exynos5433 SoC Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 35/98] mcb: mcb-pci: Only remap the 1st 0x200 bytes of BAR 0 Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 36/98] usb: serial: handle -ENODEV quietly in generic_submit_read_urb Sasha Levin
2018-10-26  8:39   ` Johan Hovold
2018-10-26 10:54     ` Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 37/98] ARM: at91/dt: sama5d4: fix the timer reg length Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 38/98] ARM: at91: sama5d3: dt: correct the sound route Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 39/98] ARM: at91/dt: sam9263: Add missing clocks to lcdc node Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 40/98] ARM: at91: board-dt-sama5: add phy_fixup to override NAND_Tree Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 41/98] fbdev/broadsheetfb: fix memory leak Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 42/98] tracing: Fix enabling of syscall events on the command line Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 43/98] perf/rapl: Fix sysfs_show() initialization for RAPL PMU Sasha Levin
2018-10-25 14:17 ` [PATCH AUTOSEL 3.18 44/98] perf/x86/intel: Fix bug for "cycles:p" and "cycles:pp" on SLM Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 45/98] perf machine: Fix __machine__findnew_thread() error path Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 46/98] perf tools: Fix statfs.f_type data type mismatch build error with uclibc Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 47/98] perf tools: Avoid build splat for syscall numbers " Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 48/98] perf tools: Fix segfault for symbol annotation on TUI Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 49/98] drivers: bus: check cci device tree node status Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 50/98] ARM: dts: disable CCI on exynos5420 based arndale-octa Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 51/98] clk: rockchip: fix deadlock possibility in cpuclk Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 52/98] quota: Fix maximum quota limit settings Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 53/98] rtnl: don't account unused struct ifla_port_vsi in rtnl_port_size Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 54/98] nfs: fix high load average due to callback thread sleeping Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 55/98] rcu: Clear need_qs flag to prevent splat Sasha Levin
2018-10-25 15:31   ` Paul E. McKenney
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 56/98] x86/irq: Check for valid irq descriptor in check_irq_vectors_for_cpu_disable() Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 57/98] of/pci: Remove duplicate kfree in of_pci_get_host_bridge_resources() Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 58/98] Btrfs: avoid syncing log in the fast fsync path when not necessary Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 59/98] pinctrl: imx25: ensure that a pin with id i is at position i in the info array Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 60/98] dm: fix AB-BA deadlock in __dm_destroy() Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 61/98] arm/arm64: KVM: Take mmap_sem in stage2_unmap_vm Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 62/98] net/mlx4_en: Remove dependency between timestamping capability and service_task Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 63/98] iommu/vt-d: Fix VM domain ID leak Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 64/98] tty: serial: fsl_lpuart: fix clearing of receive flag Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 65/98] x86/idle: Restore trace_cpu_idle to mwait_idle() calls Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 66/98] ext4: fix an ext3 collapse range regression in xfstests Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 67/98] net: ethernet: davicom: fix devicetree irq resource Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 68/98] perf bench numa: Fix to show proper convergence stats Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 69/98] MIPS: Fix up obsolete cpu_set usage Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 70/98] dm9000: Fix irq trigger type setup on non-dt platforms Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 71/98] lib: make memzero_explicit more robust against dead store elimination Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 72/98] ASoC: dapm: Don't add prefix to widget stream name Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 73/98] mtd: blkdevs: fix potential deadlock + lockdep warnings Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 74/98] selftests: Introduce a new script to generate tc batch file Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 75/98] rtlwifi: rtl8821ae: Fix system lockups on boot Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 76/98] rtlwifi: rtl8821ae: Fix " Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 77/98] clocksource/exynos_mct: Clear interrupt when cpu is shut down Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 78/98] ALSA: hda - Add headset mic support for Acer Aspire V5-573G Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 79/98] ALSA: usb-audio: Add a more accurate volume quirk for AudioQuest DragonFly Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 80/98] tty: audit: Fix audit source Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 81/98] Btrfs: do not ignore errors from btrfs_lookup_xattr in do_setxattr Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 82/98] igb: Unpair the queues when changing the number of queues Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 83/98] libata: blacklist Micron 500IT SSD with MU01 firmware Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 84/98] perf: Fix PERF_EVENT_IOC_PERIOD deadlock Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 85/98] mm: migrate: hugetlb: putback destination hugepage to active list Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 86/98] Revert "SCSI: Fix NULL pointer dereference in runtime PM" Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 87/98] x86/ldt: Fix small LDT allocation for Xen Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 88/98] PCI: Fix devfn for VPD access through function 0 Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 89/98] vfs: Make sendfile(2) killable even better Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 90/98] sctp: translate network order to host order when users get a hmacid Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 91/98] iwlwifi: pcie: correctly define 7265-D cfg Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 92/98] ovl: fix open in stacked overlay Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 93/98] igb: fix NULL derefs due to skipped SR-IOV enabling Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 94/98] KEYS: put keyring if install_session_keyring_to_cred() fails Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 95/98] USB: hub: fix up early-exit pathway in hub_activate Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 96/98] net: fix warnings in 'make htmldocs' by moving macro definition out of field declaration Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 97/98] x86/PCI: Mark Broadwell-EP Home Agent 1 as having non-compliant BARs Sasha Levin
2018-10-25 14:18 ` [PATCH AUTOSEL 3.18 98/98] unix: correctly track in-flight fds in sending process user_struct Sasha Levin

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