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commitf23cc3ba49upstream. This change fixes HS400 tuning for devices with invalid presets. SDHCI presets are not currently used for eMMC HS/HS200/HS400, but are used for DDR52. The HS400 retuning sequence is: HS400->DDR52->HS->HS200->Perform Tuning->HS->HS400 This means that when HS400 tuning happens, we transition through DDR52 for a very brief period. This causes presets to be enabled unintentionally and stay enabled when transitioning back to HS200 or HS400. Some firmware has invalid presets, so we end up with driver strengths that can cause I/O problems. Fixes:34597a3f60("mmc: sdhci-acpi: Add support for ACPI HID of AMD Controller with HS400") Signed-off-by: Raul E Rangel <rrangel@chromium.org> Acked-by: Adrian Hunter <adrian.hunter@intel.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200928154718.1.Icc21d4b2f354e83e26e57e270dc952f5fe0b0a40@changeid Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> 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.
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.