AM6442: MMCSD HS400 support in SDK

Koichiro Tashiro

Part Number: AM6442

Hi,

According to TRM (SPRUIM2D) section 12.3.5.1.2 "MMCSD Not Supported Features", HS400 DDR is not supported.

But it seems u-boot and Linux kernel recognizes mmc as HS400.
u-boot log:

=> mmcinfo
Device: mmc@fa10000
Manufacturer ID: 13
OEM: 14e
Name: S0J56
Bus Speed: 200000000
Mode: HS400 (200MHz)

Kernel log:

[    2.661436] mmc1: new HS400 MMC card at address 0001

My customer wants to know how to limit speed rate up to HS200 in case HS400 eMMC device is connected, both in u-boot and kernel.

Thanks and regards,
Koichiro Tashiro

over 1 year ago

0 Koichiro Tashiro over 1 year ago

TI__Mastermind 21150 points

Hi,

Could you also provide how to change SD card speed rate?
I know SDR104 is supported in AM64x, but the customer wants to evaluate slower speed as well.

Thanks and regards,
Koichiro Tashiro

0 Andrew Shutzberg over 1 year ago in reply to Koichiro Tashiro

TI__Intellectual 2350 points

Hey Koichiro,

My name is Andrew and I would be happy to help. Have you seen our latest Linux SDK documentation on creating new SD cards? Specifically I think this section on using custom images could be pertinent here: https://software-dl.ti.com/processor-sdk-linux/esd/AM64X/08_04_01_04/exports/docs/linux/Overview/Processor_SDK_Linux_create_SD_card.html

Best regards,

Andrew

0 Koichiro Tashiro over 1 year ago in reply to Andrew Shutzberg

TI__Mastermind 21150 points

Hi Andrew,

Thanks for your reply.
I am afraid the document you pointed out to me does not provide what my customer wants to know.
He wants to know;
- how to limit MMC speed rate up to HS200 if HS400 device is connected.
- how to configure SD speed rate

Thanks and regards,
Koichiro Tashiro

0 Andrew Shutzberg over 1 year ago in reply to Koichiro Tashiro

TI__Intellectual 2350 points

Hey Koichiro,

Thank you for the update, sorry the previous document wasn't able to be of use. Let me reach out to the team to see if we have any more directed examples/collateral that could help here.

Best regards,

Andrew

0 Koichiro Tashiro over 1 year ago in reply to Andrew Shutzberg

TI__Mastermind 21150 points

Hi Andrew,

Any news?
The customer is waiting for the answer.

Thanks and regards,
Koichiro Tashiro

0 Andrew Shutzberg over 1 year ago in reply to Koichiro Tashiro

TI__Intellectual 2350 points

Hey Koichiro,

Thanks for your patience, I was able to confirm with the team that HS400 DDR is NOT Supported for this SOC. However, as of SDK revision 8.3, this preference was still erroneously enabled in both u-boot and kernel ("mmc-hs400-1_8v" in device tree). In the latest SDK revision, 8.4, this option was disabled in Kernel, but has not been rectified in u-boot yet.

Also, here is some more detailed information on how to view SD card preferences from our Linux academy: https://dev.ti.com/tirex/explore/node?node=A__AFzIaks11.lFd1x7BS-2wg__linux_academy_am64x__7qm9DIS__LATEST&search=am64x%20sd%20card

Is there anything else we can assist with?

Best regards,

Andrew

0 Koichiro Tashiro over 1 year ago in reply to Andrew Shutzberg

TI__Mastermind 21150 points

Hi Andrew,

Could you answer below question, too?

Koichiro Tashiro said:
Could you also provide how to change SD card speed rate?
I know SDR104 is supported in AM64x, but the customer wants to evaluate slower speed as well.

Thanks and regards,
Koichiro Tashiro

0 Andrew Shutzberg over 1 year ago in reply to Koichiro Tashiro

TI__Intellectual 2350 points

Hey Koichiro,

Here is some additional reference from the AM64x evm user guide on how UHS mode is enabled/used for SD cards:

Page 30:

3.4.8.2.1 Micro SD Interface:

The processor board provides an uSD card interface connected to MMC1 port of AM64x SoC. The uSD card interface supports UHS1 operation including operations at both 1.8V and 3.3V IO levels.. The AM64x SoC includes a circuit to generate the uSD voltage based on IO level negotiation with the uSD card. For high-speed cards, ROM code of the SoC attempts to find the fastest speed that the card and controller can support and can have a transition to 1.8V. The internal SDIO LDO output from the SoC is provided on the CAP_VDDSHV_SDLDO pin. CAP_VDDSHV_SDLDO is connected to both the IO voltage of SD signals and VDDSHV_MMC1 power pins of the SoC.

https://www.ti.com/lit/ug/spruix0d/spruix0d.pdf?ts=1666211329607&ref_url=https%253A%252F%252Fwww.google.com%252F

Does this answer your question?

Best regards,

Andrew

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AM6442: MMCSD HS400 support in SDK