[linux-sunxi] [PATCH v2 1/4] dt: bindings: mmc: Document the practice of using subnodes for slots

On 1 June 2014 11:23, Hans de Goede [off-list ref] wrote:

Hi,


On 05/31/2014 10:13 PM, Olof Johansson wrote:

quoted

On Sat, May 31, 2014 at 12:03 PM, Hans de Goede [off-list ref]
wrote:

quoted

The following existing MMC host controller bindings use slot subnodes:

Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt
Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt
Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
Documentation/devicetree/bindings/mmc/socfpga-dw-mshc.txt
Documentation/devicetree/bindings/mmc/atmel-hsmci.txt
Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt

This commit documents this practice in the standard mmc bindings
documentation.

Signed-off-by: Hans de Goede <redacted>

There are today only two drivers that use this kind of binding, dw_mmc
and the at91 one.

Correct.

quoted

Neither seems to actually ever have been used with
more than one slot. I doubt anyone building an exynos-based system
will ever do a multi-slot solution, and it seems that the at91 driver
doesn't actually handle more than one slot.

I'm personally not that excited about complicating the bindings by
opening up for this -- I would rather work towards removing the
concept of slots if it's one of those things that are going to remain
unused. We have actually been talking about reworking the dw_mmc
binding to remove the slot concept (and simplify the driver by doing
so).

I'm fine with removing the slot subnode, I added it because of it being
brought up in the powerup sequence discussion. I explicitly asked there
if adding such a subnode level was seen as desirable but nobody
answered :|

Anyways, either way works for me. I can do a v3 dropping the slot subnode
level again. I would really like to move forward with a decision on how-to
represent non probable info for sdio devices in device nodes. So do you
have any other remarks other then that the slot subnode should be dropped ?
And if not can you please review and ack (*) v3 of this patch-set once
I've send it?

Chris Ball and Ulf Hansson, what is your take on this, are you willing to
take this patch set? And do you want it with or without the slot subnodes ?

I certainly appreciate you working actively on this Hans, I will look
into the patchset as soon as I can.

I share Olof's view about the slot nodes, we must not add DT bindings
that isn't really needed.

Regarding the slot subnodes; Jaehoon Chung recently posted a patchset
for adding the parsing of it, intended for dwmmc. I withdraw my ack
for it, and let's try to go in the other direction instead.

[PATCHv3 0/4] mmc: fixed the mmc_of_parse for dwmmc.

Thus I suggest we should clean-up host drivers to support only one
card per host, and entirely skip the slot concept.

Kind regards
Uffe

Thanks & Regards,

Hans


*) Assuming you don't find any issues