MMC 4.x support in SD Bus driver RRS feed

  • Question

  • Hi,

    the current SD Bus driver in CE5 and 6 (PUBLIC\COMMON\OAK\DRIVERS\SDCARD) doesn't support MMC 4.x specification yet. Such cards work because they are backwards-compatible, but there's a major lack - the support of Dual Data Rate cards, especially enabling the 4- and 8-bit bus width mode (SWITCH_FUNCTION to send BUS_WIDTH command to set the respective EXT_CSD field). This has a considerable performance impact.
    Note: do not confuse this with 4-bit SD cards, which work properly. This relates to newer MMC/eMMC cards only (
    MMCA 4.x).

    Is Microsoft acknowledging this and are there any plans to add support of this standard in a future SD Bus driver ?


    Friday, June 29, 2012 8:43 AM

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