Loic Poulain a89e7bcb18 mmc: sdhci-msm: Disable CDR function on TX
The Clock Data Recovery (CDR) circuit allows to automatically adjust
the RX sampling-point/phase for high frequency cards (SDR104, HS200...).
CDR is automatically enabled during DLL configuration.
However, according to the APQ8016 reference manual, this function
must be disabled during TX and tuning phase in order to prevent any
interferences during tuning challenges and unexpected phase alteration
during TX transfers.

This patch enables/disables CDR according to the current transfer mode.

This fixes sporadic write transfer issues observed with some SDR104 and
HS200 cards.

Inspired by sdhci-msm downstream patch:
https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/432516/

Reported-by: Leonid Segal <leonid.s@variscite.com>
Reported-by: Manabu Igusa <migusa@arrowjapan.com>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
2018-12-17 08:26:24 +01:00
2018-10-31 08:54:14 -07:00
2018-12-16 15:46:55 -08:00

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.

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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