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| author | Hebbar, Gururaja <gururaja.hebbar@ti.com> | 2012-11-19 20:29:58 +0400 |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2012-12-06 22:54:56 +0400 |
| commit | cd587096c0e2b85a67e77721a753679bac89b394 (patch) | |
| tree | 22ae2292f85cb8d36530535bc087bacdb8889158 /Documentation/devicetree | |
| parent | dc7745bd32272a614a6598c05db4510548ef18f2 (diff) | |
| download | linux-cd587096c0e2b85a67e77721a753679bac89b394.tar.xz | |
mmc: omap_hsmmc: Enable HSPE bit for high speed cards
HSMMC IP on AM33xx need a special setting to handle High-speed cards.
Other platforms like TI81xx, OMAP4 may need this as-well. This depends
on the HSMMC IP timing closure done for the high speed cards.
From AM335x TRM (SPRUH73F - 18.3.12 Output Signals Generation):
The MMC/SD/SDIO output signals can be driven on either falling edge or
rising edge depending on the SD_HCTL[2] HSPE bit. This feature allows
to reach better timing performance, and thus to increase data transfer
frequency.
There are few pre-requisites for enabling the HSPE bit
- Controller should support High-Speed-Enable Bit and
- Controller should not be using DDR Mode and
- Controller should advertise that it supports High Speed in
capabilities register and
- MMC/SD clock coming out of controller > 25MHz
Signed-off-by: Hebbar, Gururaja <gururaja.hebbar@ti.com>
Signed-off-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'Documentation/devicetree')
| -rw-r--r-- | Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt index be76a23b34c4..ed271fc255b2 100644 --- a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt +++ b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt @@ -19,6 +19,7 @@ ti,dual-volt: boolean, supports dual voltage cards "supply-name" examples are "vmmc", "vmmc_aux" etc ti,non-removable: non-removable slot (like eMMC) ti,needs-special-reset: Requires a special softreset sequence +ti,needs-special-hs-handling: HSMMC IP needs special setting for handling High Speed Example: mmc1: mmc@0x4809c000 { |