Re: OMAP35x MMC Host Controller compatibility with SDXC?

[Balaji T K <balajitk@ti.com>]

On Wednesday 18 September 2013 02:32 AM, Kevyn-Alexandre Paré wrote:
> Hi,
>
> My question is related to the drivers/mmc/host/omap_hsmmc.c host
> controller compatibility with SDXC for the OMAP35x?
>
> Reading the TRM for OMAP35x:
> http://www.ti.com/lit/ug/spruf98x/spruf98x.pdf
>
> It's said that:
> - Full compliance with SD command/response sets as defined in the SD
> Memory Card Specifications, v2.0 including high-capacity SDHC cards up
> to 32GB.
>
> - Full compliance with sets as defined in the SD Card Specification,
> Part A2, SD Host Controller Standard Specification, v2.00
>
> It doesn't mention the SDXC?
> I'm trying to found my way through all the spec of sdcard.org.
>
> I'm still wondering why using SDXC of 64GB is working and doesn't pop
> a WARNING message and if it's safe??
>
> My test shows that I'm having some timeout in some cases (v3.4.60):
> omap_hsmmc omap_hsmmc.0: IRQ Status is 18000
> omap_hsmmc omap_hsmmc.0: MMC IRQ 0x18000 : ERRI CTO
> mmc0: req done (CMD52): -110: 00000000 00000000 00000000 00000000
> mmc0: starting CMD52 arg 80000c08 flags 00000195
>
> omap_hsmmc omap_hsmmc.0: mmc0: CMD5, argument 0x00000000
> omap_hsmmc omap_hsmmc.0: IRQ Status is 18000
> omap_hsmmc omap_hsmmc.0: MMC IRQ 0x18000 : ERRI CTO
> mmc0: req failed (CMD5): -110, retrying...
>
> mmc1: starting CMD8 arg 000001aa flags 000002f5
> omap_hsmmc omap_hsmmc.1: mmc1: CMD8, argument 0x000001aa
> mmc0: starting CMD18 arg 00020000 flags 000000b5
> omap_hsmmc omap_hsmmc.1: IRQ Status is 18000
> omap_hsmmc omap_hsmmc.1: MMC IRQ 0x18000 : ERRI CTO
> mmc1: req done (CMD8): -110: 00000000 00000000 00000000 00000000
>
> So CMD 52,5 and 8 gives me timeout...

For SD cards, these cmd's are expected to timeout during card initialization.

>
> Looking at the 3.11.1 there is 2 more validation for UHS that are not in 3.4.60:
> omap_hsmmc_set_clock  // Enable High-Speed Support
> omap_set_bus_width
>

Those changes are not for SD3.0 speed modes

> Is it safe to use SDXC with OMAP35x or not? Should this pop a error message?

SDXC cards should work albeit at High Speed mode (as in SD2.0).
Refer to [1] for card size Vs speed mode/SD spec version.
Can you check if the filesystem type on SDXC card
is supported by the system software running on OMAP35x.

[1]
https://www.sdcard.org/consumers/speed/bus_speed/

>
> Best Regards,
>
> -KA
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