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Like many i2c-hid touchscreen controllers, the Elan eKTH6915 controller has a reset gpio. For the Goodix GT7375P touchscreen the decision was to add a new binding rather than trying to add a new GPIO to the existing i2c-hid binding. We'll follow the lead and do it here, too. SIDE NOTE: the Elan eKTH6915 is a touchscreen _controller_ that's included as a part on some touchscreens. The reset line isn't truly necessary for the functioning of the touchscreen, so it's possible that some designs won't have it hooked up and will just guarantee the power sequencing requirements with RLC circuits. Thus, we'll mark the reset gpio as optional. Note that if the reset GPIO isn't used there's actually no true need to use the "elan,ekth6915" compatible instead of the "hid-over-i2c" on Linux. However: - Officially using just "hid-over-i2c" for this device violates the existing "hid-over-i2c" bindings. The bindings say that you're not supposed to use "post-power-on-delay-ms" without specifying a more specific compatible. Currently the Linux driver doesn't enforce this, but it violates the bindings to just use "hid-over-i2c". ...and if you're going to add a more specific compatible anyway, might as well do it right. - Using this compatible means we don't need to specify "hid-descr-addr" since it's inferred from the compatible. - Using this compatible means that the regulator names match the names on the Elan datasheet (vcc33 / vccio) vs the generic hid-over-i2c (vdd / vddl). Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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.