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Furquan Shaikh 0b471aaa0e mfd: intel-lpss: Put I2C and SPI controllers into reset state on suspend 
Commit 274e43edcd ("mfd: intel-lpss: Do not put device in reset
state on suspend") changed the behavior on suspend by not putting LPSS
controllers into reset. This was done because S3/S0ix fail if UART
device is put into reset and no_console_suspend flag is enabled.

Because of the above change, I2C controller gets into a bad state if
it observes that the I2C lines are pulled low when power to I2C device
is cut off during suspend (generally, I2C lines are pulled to power
rail of the I2C device in order to ensure that there is no leakage
because of the pulls when device is turned off). This results in the
controller timing out for all future I2C operations after resume. It
is primarily because of the following sequence of operations:

During suspend:
1. I2C controller is disabled, but it is not put into reset.
2. Power to I2C device is cut off.
3. #2 results in the I2C lines being pulled low.

==> At this point the I2C controller gets into a bad state

On resume:
1. Power to I2C device is enabled.
2. #2 results in the I2C lines being pulled high.
3. I2C controller is enabled.

However, even after enabling the I2C controller, all future I2C xfers
fail since the controller is in a bad state and does not attempt to
make any transactions and hence times out.

In order to ensure that the controller does not get into a bad state,
this change puts it into reset if the controller type is not
UART. With this change, the order of operations is:

During suspend:
1. I2C controller is disabled and put into reset.
2. Power to I2C device is cut off.
3. #2 results in the I2C lines being pulled low.

On resume:
1. Power to I2C device is enabled.
2. #2 results in the I2C lines being pulled high.
3. I2C controller is enabled and taken out of reset.

Signed-off-by: Furquan Shaikh <furquan@google.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2017-09-05 08:46:01 +01:00
arch Merge branches 'ib-mfd-arm-i2c-4.14', 'ib-mfd-arm-usb-video-4.14', 'ib-mfd-hwmon-4.14', 'ib-mfd-iio-pwm-4.14', 'ib-mfd-input-rtc-4.14', 'ib-mfd-many-4.14' and 'ib-mfd-pinctrl-regulator-4.14' into ibs-for-mfd-merged 2017-09-05 08:45:36 +01:00
block blk-mq-debugfs: Add names for recently added flags 2017-08-25 08:07:44 -06:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: algif_skcipher - only call put_page on referenced and used pages 2017-08-22 14:45:48 +08:00
Documentation mfd: Add ROHM BD9571MWV-M PMIC DT bindings 2017-09-05 08:46:01 +01:00
drivers mfd: intel-lpss: Put I2C and SPI controllers into reset state on suspend 2017-09-05 08:46:01 +01:00
firmware
fs Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6 2017-09-01 20:57:27 -07:00
include mfd: Add support for TPS68470 device 2017-09-05 08:46:01 +01:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc: add missing container_of()s for randstruct 2017-08-02 17:16:12 -07:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-03 09:30:40 -07:00
lib Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-09-01 10:30:03 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2017-08-31 17:56:56 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-09-01 12:49:03 -07:00
samples samples/bpf: fix bpf tunnel cleanup 2017-07-31 22:02:47 -07:00
scripts scripts/dtc: fix '%zx' warning 2017-08-31 16:33:15 -07:00
security Now that IPC and other changes have landed, enable manual markings for 2017-07-19 08:55:18 -07:00
sound mfd: twl: Move header file out of I2C realm 2017-09-04 14:41:02 +01:00
tools NTB bug fixes to address an incorrect ntb_mw_count reference in the NTB 2017-08-27 17:01:54 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt KVM: update to new mmu_notifier semantic v2 2017-08-31 16:13:00 -07:00
.cocciconfig
.get_maintainer.ignore
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CREDITS
Kbuild
Kconfig
MAINTAINERS mfd: Add ROHM BD9571MWV-M MFD PMIC driver 2017-09-05 08:46:00 +01:00
Makefile Linux 4.13 2017-09-03 13:56:17 -07:00
README

README 

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.