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    • 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
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