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ec03c21043
The infamous commitc440eee1a7("Staging: staging: fbtft: Switch to the GPIO descriptor interface") broke GPIO handling completely. It has already four commits to rectify and it seems not enough. In order to fix the mess here we: 1) Set default to "inactive" for all requested pins 2) Fix CS#, RD#, and WR# pins polarity since it's active low and GPIO descriptor interface takes it into consideration from the Device Tree or ACPI 3) Consolidate chip activation (CS# assertion) under default ->reset() callback To summarize the expectations about polarity for GPIOs: RD# Low WR# Low CS# Low RESET# Low DC or RS High RW High Data 0 .. 15 High See also Adafruit learning course [1] for the example of the schematics. While at it, drop unneeded NULL checks, since GPIO API is tolerant to that. [1]: https://learn.adafruit.com/adafruit-2-8-and-3-2-color-tft-touchscreen-breakout-v2/downloads Fixes:92e3e88488("Staging: fbtft: Fix GPIO handling") Fixes:b918d1c270("Staging: fbtft: Fix reset assertion when using gpio descriptor") Fixes:dbc4f989c8("Staging: fbtft: Fix probing of gpio descriptor") Fixes:c440eee1a7("Staging: fbtft: Switch to the gpio descriptor interface") Cc: Jan Sebastian Götte <linux@jaseg.net> Cc: Nishad Kamdar <nishadkamdar@gmail.com> Reviewed-by: Phil Reid <preid@electromag.com.au> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20210503172114.27891-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.