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UHS (SD-Card) clock frequency

Question asked by Ofer Federovsky on Jul 14, 2014
Latest reply on Mar 12, 2015 by Zongbiao Liao

Hi,

 

We have a custom board and we are trying to debug UHS.

Our board support switching to 1.8v, and it seems that we do work in UHS, but the SD clock frequency is ~50MHz.

 

From dmesg:

[    3.924535] sdhci: Secure Digital Host Controller Interface driver

[    3.930721] sdhci: Copyright(c) Pierre Ossman

[    3.935235] mmc0: no vmmc regulator found

[    3.939500] mmc0: SDHCI controller on platform [sdhci-esdhc-imx.0] using DMA

[    4.083747] regulator_init_complete: vmmc: incomplete constraints, leaving on

[    4.134227] sdhci_start_signal_voltage_switch

[    4.177389] mmc0: new ultra high speed SDHC card at address aaaa

[    4.184295] mmcblk0: mmc0:aaaa SU08G 7.40 GiB

[    4.190366]  mmcblk0: p1 p2

 

From our board-file:

static const struct esdhc_platform_data mx6_arm2_sd1_data __initconst = {

  .cd_gpio = SEEMORE_SD1_CD,

  .cd_type = ESDHC_CD_GPIO,

  .support_8bit   = 1,

  .keep_power_at_suspend  = 1,

  .cd_gpio_inverted = 1,

  .support_18v = 1,

};


Custom board with i.mx6q, Linux 3.0.35 4.1.0.


What should I do in order to switch to higher frequencies (104MHz)?


Thanks!

Ofer


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