Re: SD card specification and eSDHC controller

[Christian Loehle <christian.loehle@arm.com>]

On 28/03/2024 13:13, Patryk wrote:
> Hi,
> I've got a question regarding sd cards, their specifications, and the
> ability to support them by a host controller.
> In my eSDHC (NXP LS1028a soc) features summary I can find the following:
> - Conforms to the SD Host controller standard specification version
> 3.0, including test event register support
> - Compatible with the SD memory card specification version 3.01, and
> supports the high-capacity SD memory card
> - Compatible with the SDIO card specification version 3.0
> 
> I have found that SD cards compatible with SD card specification 4.10
> and higher support something like an extension register and in
> particular power management. I've searched through kernel code and
> found that these registers are parsed by the let's say generic part of
> sd/mmc subsystem not by the host controller driver.
> Does it mean that I can connect the SD card compatible with spec 4.10
> and expect that the sd/mmc subsystem will use power management
> features if the card supports them?
Yes. mmc core will handle it if the card supports it.
"power management features" is a bit misleading, it's
SD_EXT_POWER_OFF_NOTIFY.

> Best regards
> Patryk
>