Paul Geurts a58addf5d2 NFC: trf7970a: Ignore antenna noise when checking for RF field
[ Upstream commit a9bc28aa4e64320668131349436a650bf42591a5 ]

The main channel Received Signal Strength Indicator (RSSI) measurement
is used to determine whether an RF field is present or not. RSSI != 0
is interpreted as an RF Field is present. This does not take RF noise
and measurement inaccuracy into account, and results in false positives
in the field.

Define a noise level and make sure the RF field is only interpreted as
present when the RSSI is above the noise level.

Fixes: 851ee3cbf8 ("NFC: trf7970a: Don't turn on RF if there is already an RF field")
Signed-off-by: Paul Geurts <paul.geurts@prodrive-technologies.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Link: https://patch.msgid.link/20260422100930.581237-1-paul.geurts@prodrive-technologies.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>
2026-06-29 10:46:09 +02:00

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.
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