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

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On 15 September 2017 at 20:02, Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
> 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-XS board 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
>
> Looking forward to comments about this approach.
>
> All the best,
>
>    Wolfram
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=51ced59cc02e0d08f61772c888480b9b1749cef1
>
> Wolfram Sang (3):
>   mmc: describe new eMMC binding for fixed driver type
>   mmc: parse new binding for eMMC fixed driver type
>   arm64: renesas: salvator-xs: set driver type for eMMC
>
>  Documentation/devicetree/bindings/mmc/mmc.txt      |  3 +++
>  .../arm64/boot/dts/renesas/r8a7795-salvator-xs.dts |  4 ++++
>  drivers/mmc/core/core.c                            | 28 ++++++++++++++++++----
>  drivers/mmc/core/host.c                            | 11 ++++++++-
>  include/linux/mmc/host.h                           |  2 ++
>  5 files changed, 42 insertions(+), 6 deletions(-)

Looks good to me. Awaiting a v2 before applying allowing you to take
care of the comment from Rob.

Kind regards
Uffe
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