• Hebbar, Gururaja's avatar
    mmc: omap_hsmmc: Enable HSPE bit for high speed cards · cd587096
    Hebbar, Gururaja authored
    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: default avatarHebbar, Gururaja <gururaja.hebbar@ti.com>
    Signed-off-by: default avatarVenkatraman S <svenkatr@ti.com>
    Signed-off-by: default avatarChris Ball <cjb@laptop.org>
    cd587096
omap_hsmmc.c 53.9 KB