mmc: sdhci-msm: improve tuning process

In newer hardware, the tuning process is not able to always
find a reliable phase to use for sampling data. This is mostly
due to hardware. This problem manifests itself as all successful
tuning phases, which means that the phase choosen could be a bad
one but is not identified as such at the time of tuning. So in
order to work around this, rely on optional drive types implemented
by the eMMC card, in addition to the mandatory drive type (50 ohm).

By using drive types supported by the card, when all phases are
sucessful in tuning, change drive type to a different value in the
list of supported drive types and retune. This will continue for all
tuning phases until a valid one is found. After that the drive type
is reset to the default one, if changed.

Change-Id: I348fb30daa43d97c58f83f7e4a22019f94ef4954
Signed-off-by: Krishna Konda <kkonda@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>

0 files changed, 0 insertions, 0 deletions