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5fa4086987
linux/drivers
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Thierry Reding 5fa4086987 rtc: tegra: Implement clock handling 
Accessing the registers of the RTC block on Tegra requires the module
clock to be enabled. This only works because the RTC module clock will
be enabled by default during early boot. However, because the clock is
unused, the CCF will disable it at late_init time. This causes the RTC
to become unusable afterwards. This can easily be reproduced by trying
to use the RTC:

	$ hwclock --rtc /dev/rtc1

This will hang the system. I ran into this by following up on a report
by Martin Michlmayr that reboot wasn't working on Tegra210 systems. It
turns out that the rtc-tegra driver's ->shutdown() implementation will
hang the CPU, because of the disabled clock, before the system can be
rebooted.

What confused me for a while is that the same driver is used on prior
Tegra generations where the hang can not be observed. However, as Peter
De Schrijver pointed out, this is because on 32-bit Tegra chips the RTC
clock is enabled by the tegra20_timer.c clocksource driver, which uses
the RTC to provide a persistent clock. This code is never enabled on
64-bit Tegra because the persistent clock infrastructure does not exist
on 64-bit ARM.

The proper fix for this is to add proper clock handling to the RTC
driver in order to ensure that the clock is enabled when the driver
requires it. All device trees contain the clock already, therefore
no additional changes are required.

Reported-by: Martin Michlmayr <tbm@cyrius.com>
Acked-By Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2017-01-23 00:46:55 +01:00
..
accessibility
acpi Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
amba
android
ata Merge branch 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2016-12-13 15:30:50 -08:00
atm Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
auxdisplay
base avoid spurious "may be used uninitialized" warning 2016-12-25 14:56:58 -08:00
bcma
block ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
bluetooth Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-16 10:24:44 -08:00
bus cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
cdrom Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
char clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
clk Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2016-12-15 16:06:15 -08:00
clocksource Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
connector
cpufreq Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
cpuidle Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
crypto crypto: add virtio-crypto driver 2016-12-16 00:13:32 +02:00
dax libnvdimm for 4.10 2016-12-18 15:49:10 -08:00
dca
devfreq
dio Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
dma ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
dma-buf
edac Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
eisa
extcon sound updates for 4.10-rc1 2016-12-14 11:14:28 -08:00
firewire
firmware firmware: dmi_scan: Always show system identification string 2016-12-19 10:01:47 +01:00
fmc
fpga
gpio - New Device Support 2016-12-19 08:16:26 -08:00
gpu ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
hid Merge branches 'for-4.10/asus', 'for-4.10/cp2112', 'for-4.10/i2c-hid-nopower', 'for-4.10/intel-ish', 'for-4.10/mayflash', 'for-4.10/microsoft-surface-3', 'for-4.10/multitouch', 'for-4.10/sony', 'for-4.10/udraw-ps3', 'for-4.10/upstream' and 'for-4.10/wacom/generic' into for-linus 2016-12-14 10:12:26 +01:00
hsi
hv clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
hwmon
hwspinlock
hwtracing coresight/etm3/4x: Consolidate hotplug state space 2016-12-25 10:47:44 +01:00
i2c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ide Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
idle Power management material for v4.10-rc1 2016-12-13 10:41:53 -08:00
iio ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
infiniband Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
input ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
iommu More ACPI updates for v4.10-rc1 2016-12-22 10:19:32 -08:00
ipack
irqchip Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
isdn Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
leds cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
lguest Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
lightnvm Char/Misc driver patches for 4.10-rc1 2016-12-13 12:11:01 -08:00
macintosh Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mailbox ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
mcb
md Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
media ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
memory
memstick Merge branch 'for-4.10/block' of git://git.kernel.dk/linux-block 2016-12-13 10:19:16 -08:00
message Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mfd - New Device Support 2016-12-19 08:16:26 -08:00
misc Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mmc Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mtd Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
net Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
nfc
ntb ntb_transport: Remove unnecessary call to ntb_peer_spad_read 2016-12-23 16:11:07 -05:00
nubus Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
nvdimm libnvdimm for 4.10 2016-12-18 15:49:10 -08:00
nvme nvme : Use correct scnprintf in cmb show 2016-12-19 08:35:24 -07:00
nvmem
of pci-v4.10-changes 2016-12-15 12:46:48 -08:00
oprofile Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
parisc Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
parport Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
pci ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
pcmcia
perf cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
phy SCSI misc on 20161213 2016-12-14 10:49:33 -08:00
pinctrl ARM: DT updates for v4.10 2016-12-15 15:50:24 -08:00
platform ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
pnp Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
power ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
powercap
pps
ps3
ptp
pwm pwm: Changes for v4.10-rc1 2016-12-15 11:45:13 -08:00
rapidio
ras
regulator - New Device Support 2016-12-19 08:16:26 -08:00
remoteproc
reset ARM: SoC driver updates for v4.10 2016-12-15 16:03:25 -08:00
rpmsg rpmsg updates for v4.10 2016-12-13 08:52:45 -08:00
rtc rtc: tegra: Implement clock handling 2017-01-23 00:46:55 +01:00
s390 ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
sbus Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
scsi Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
sfi
sh
sn
soc powerpc updates for 4.10 2016-12-16 09:26:42 -08:00
spi dmaengine updates for 4.10-rc1 2016-12-14 20:42:45 -08:00
spmi
ssb
staging staging/lustre/libcfs: Convert to hotplug state machine 2016-12-25 10:47:43 +01:00
target Merge branch 'scsi-target-for-v4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/bvanassche/linux 2016-12-21 10:16:05 -08:00
tc
thermal Power management material for v4.10-rc1 2016-12-13 10:41:53 -08:00
thunderbolt Char/Misc driver patches for 4.10-rc1 2016-12-13 12:11:01 -08:00
tty Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
uio
usb ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
uwb
vfio powerpc updates for 4.10 2016-12-16 09:26:42 -08:00
vhost Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-16 10:24:44 -08:00
video Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
virt
virtio virtio_mmio: Set dev.release() to avoid warning 2016-12-16 00:13:39 +02:00
vlynq
vme
w1
watchdog Watchdog updates for v4.10 2016-12-24 11:27:45 -08:00
xen cpu/hotplug: Cleanup state names 2016-12-25 10:47:44 +01:00
zorro Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
Kconfig
Makefile