SD card specification and eSDHC controller

SD card specification and eSDHC controller

[Patryk]

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?

Best regards
Patryk

Re: SD card specification and eSDHC controller

[Christian Loehle]

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
> 

Re: SD card specification and eSDHC controller

[Patryk]

Hi, thanks a lot for the response

czw., 28 mar 2024 o 14:25 Christian Loehle <christian.loehle@arm.com>
napisał(a):
> 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.

So, this will work even though my SD Host controller is: "Compatible
with the SD memory card specification version 3.01", yes?
Does this mean that the compatibility concerns things like physical
connection, and supported speeds whereas things like
"SD_EXT_POWER_OFF_NOTIFY" are solely software features that can
handled by mmc core if sd card firmware supports it?

Best regards
Patryk