[PATCH v2 0/3] mmc: support eMMC driver type selection with DT

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

Some of the Renesas R-Car boards need to set the eMMC driver type to type 1 to
get stable HS200/400 speeds (HS400 support not upstream yet). Because the eMMC
memories are fixed (and thus the drive type), I decided to implement the DT
setup in a similar fashion to ACPI [1]. While implementing, I realized that all
I did was not Renesas specific but generic, so I ended up putting it into the
core.

So, whenever the new property (introduced in patch 1) is used, and there is no
host driver specific select_drive_strength callback, then the generic callback
(introduced in patch 2) is used. An example usage can be found in patch 3.

Note that currently only eMMC is handled, but the code is designed for easy SD
addition if that ever becomes necessary.

A branch for the Salvator-X(S) boards can be found here:

git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/topic/emmc-drive-strength

A wiki page describing my test procedure can be found here:

http://elinux.org/Tests:eMMC-fixed-drive-strength

Changes since RFC v1 are described per patch. It is mainly a rebase to mmc/next
and addressing Rob's comments. Tested on Salvator-X (R-Car H3 ES1.0) and
Salvator-XS (R-Car H3 ES2.0).

I know that patch 3 needs to go via Simon, but I still include it here for
completeness.

Thanks,

   Wolfram

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=51ced59cc02e0d08f61772c888480b9b1749cef1


Wolfram Sang (3):
  dt-bindings: mmc: describe new eMMC binding for fixed driver type
  mmc: parse new binding for eMMC fixed driver type
  arm64: renesas: salvator: set driver type for eMMC

 Documentation/devicetree/bindings/mmc/mmc.txt    |  3 +++
 arch/arm64/boot/dts/renesas/salvator-common.dtsi |  1 +
 drivers/mmc/core/core.c                          | 28 +++++++++++++++++++-----
 drivers/mmc/core/host.c                          | 11 +++++++++-
 include/linux/mmc/host.h                         |  2 ++
 5 files changed, 39 insertions(+), 6 deletions(-)

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2.11.0