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commit b086a46dae48829e11c0c02580e30d920b76743c upstream.
When two chip-selects are configured in the device tree, and the second is
a non-native GPIO, both the GPIO-based chip-select and the first native
chip-select may be asserted simultaneously. This double assertion causes
incorrect read and write operations.
The issue occurs because when nfc->ncs <= 2, nfc->spare_cs is always
initialized to 0 due to static initialization. Consequently, when the
second chip-select (GPIO-based) is selected in anfc_assert_cs(), it is
detected by anfc_is_gpio_cs(), and nfc->native_cs is assigned the value 0.
This results in both the GPIO-based chip-select being asserted and the
NAND controller register receiving 0, erroneously selecting the native
chip-select.
This patch resolves the issue, as confirmed by oscilloscope testing with
configurations involving two or more chip-selects in the device tree.
Fixes: acbd3d0945 ("mtd: rawnand: arasan: Leverage additional GPIO CS")
Cc: stable@vger.kernel.org
Signed-off-by: Maciej Andrzejewski <maciej.andrzejewski@m-works.net>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.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.