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
