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921daeeca9
One some devices the GPIO should output the inverted value from what
device-drivers / ACPI code expects. The reason for this is unknown,
perhaps these systems use an external buffer chip on the GPIO which
inverts the signal. The BIOS makes this work by setting the
CHV_PADCTRL1_INVRXTX_TXDATA flag.
Before this commit we would unconditionally clear all INVRXTX flags,
including the CHV_PADCTRL1_INVRXTX_TXDATA flag when a GPIO is requested
by a driver (from chv_gpio_request_enable()).
This breaks systems using this setup. Specifically it is causing
problems for systems with a goodix touchscreen, where the BIOS sets the
INVRXTX_TXDATA flag on the GPIO used for the touchscreen's reset pin.
The goodix touchscreen driver by defaults configures this pin as input
(relying on the pull-up to keep it high), but the clearing of the
INVRXTX_TXDATA flag done by chv_gpio_request_enable() causes it to be
driven low for a brief time before the GPIO gets set to input mode.
This causes the touchscreen controller to get reset. On most CHT devs
with this touchscreen this leads to:
[ 31.596534] Goodix-TS i2c-GDIX1001:00: i2c test failed attempt 1: -121
The driver retries this though and then everything is fine. But during
reset the touchscreen uses its interrupt pin as bootstrap to determine
which i2c address to use and on the Acer One S1003 the spurious reset
caused by the clearing of the INVRXTX_TXDATA flag causes the controller
to come back up again on the wrong i2c address, breaking things.
This commit fixes both the -121 errors, as well as the total breakage
on the Acer One S1003, by making chv_gpio_clear_triggering() not clear
the INVRXTX_TXDATA flag if the pin is already configured as a GPIO.
Note that chv_pinmux_set_mux() does still unconditionally clear the
flag, so this only affects GPIO usage.
Fixes:
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.