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, its value will be used regardless of a potentially implemented host driver specific select_drive_strength callback (patch 2). An example usage can be found in patch 3. Note that currently only eMMC is handled 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 v2 are described per patch. It is mainly a rebase to mmc/next and addressing Ulf'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/host.c | 13 ++++++++++++- drivers/mmc/core/mmc.c | 11 ++++++++--- include/linux/mmc/host.h | 2 ++ 5 files changed, 26 insertions(+), 4 deletions(-) -- 2.11.0
