About eMMC's HS400 support in Android's "IMX6_M6.0.1_2.1.0"

[yasushihasegawa]

Dear Community members,

Our customer is mass producing using i.MX7Solo and Android's "IMX6_M6.0.1_2.1.0".
Customer is verifying that the eMMC device will be revised.

[Question.1]
Does this "IMX6_M6.0.1_2.1.0" support HS400 of eMMC?

==> [information]
  The following files have been confirmed.
    myandroid / kernel_imx / Documentation / devicetree / bindings / mmc / mmc.txt
  I confirm that there is the following statement.
    -Mmc-hs400-1_8v: eMMC HS400 mode (1.8 V I / O) is supported

[Question.2]
In "6.6.2.3 HS400 timing mode selection" on page 66 of "JEDEC STANDARD JESD 84-B51", it is described that the strobe point is tuned in HS200 mode and then changed to HS400 mode.
Is this flow supported by Android's "IMX6_M6.0.1_2.1.0"?

Best Regards,

Yasushi Hasegawa

[igorpadykov]

Hi Yasushi

[Question.1] Does this "IMX6_M6.0.1_2.1.0" support HS400 of eMMC?

yes, one can look at mmc driver sources:

esdhc_set_uhs_signaling(), esdhc_set_strobe_dll()
https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/mmc/host/sdhci-esdhc-imx.c?h=imx_4...

General driver description can found in Chapter 32 MMC/SD/SDIO Host Driver

attached Linux Manual.

>[Question.2] Is this flow supported by Android's "IMX6_M6.0.1_2.1.0"?

yes mmc driver follows mmc jedec specification

Best regards
igor
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[yasushihasegawa]

Dear igor-san,

Thank you for answering.

>yes, one can look at mmc driver sources:

>esdhc_set_uhs_signaling(), esdhc_set_strobe_dll()
>https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/mmc/host/sdhci-esdhc-imx.c?h=imx_4.1.15_2.0.0_ga

But your answer seems like an answer about Linux's BSP.

The drivers that customers are aware of and referring to are the following paths:
      //myandroid/bootable/bootloader/uboot-imx/drivers/mmc/mmc.c

Although the above driver file does not seem to correspond to HS200/HS400, i.MX7Solo operates according to HS400 when the .dts file is set to HS400.

I am sorry for the basic questions, but please let me know.

[Question.3]

(Q3-1) Is the contents described in the .dts file applied correctly when uboot is executed?

(Q3-2) Are the following answers from you linked to u-Boot?

>yes, one can look at mmc driver sources:

>esdhc_set_uhs_signaling(), esdhc_set_strobe_dll()
>https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/mmc/host/sdhci-esdhc-imx.c?h=imx_4.1.15_2.0.0_ga

Best Regards,
Yasushi Hasegawa

[igorpadykov]

Hi Yasushi

 - android is based on linux, please refer to attached Reelase Notes Table 2. Features:

"Based on Linux® OS BSP L5.1.15_1.2.0-ga release"

>(Q3-2) Are the following answers from you linked to u-Boot?

below link is linux sources, not uboot

https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/mmc/host/sdhci-esdhc-imx.c?h=imx_4...

uboot v2015.04  should be used with that release:

uboot-imx - i.MX U-Boot 

Best regards
igor