8b488ef295
According to datasheets, chips like mXT1386 have a WAKE line, it is used to wake the chip up from deep sleep mode before communicating with it via the I2C-compatible interface. If the WAKE line is connected to a GPIO line, the line must be asserted 25 ms before the host attempts to communicate with the controller. If the WAKE line is connected to the SCL pin, the controller will send a NACK on the first attempt to address it, the host must then retry 25 ms later. Implement the wake-up methods in the driver. Touchscreen now works properly on devices like Acer A500 tablet, fixing problems like this: atmel_mxt_ts 0-004c: __mxt_read_reg: i2c transfer failed (-121) atmel_mxt_ts 0-004c: mxt_bootloader_read: i2c recv failed (-121) atmel_mxt_ts 0-004c: Trying alternate bootloader address atmel_mxt_ts 0-004c: mxt_bootloader_read: i2c recv failed (-121) atmel_mxt_ts: probe of 0-004c failed with error -121 Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Jiada Wang <jiada_wang@mentor.com> Signed-off-by: Dmitry Osipenko <digetx@gmail.com> Link: https://lore.kernel.org/r/20210302102158.10533-3-digetx@gmail.com Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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.