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: 34597a3f60b1 ("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>
f23cc3ba49