[PATCH v5 1/4] mmc: meson: Document Amlogic Meson MMC DT bindings

On Thu, Mar 3, 2016 at 11:17 PM, Rob Herring [off-list ref] wrote:

On Sat, Feb 27, 2016 at 07:01:45PM +0100, Carlo Caione wrote:

quoted

From: Carlo Caione <redacted>

Signed-off-by: Carlo Caione <redacted>
---
 .../devicetree/bindings/mmc/meson-mmc.txt          | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mmc/meson-mmc.txt

diff --git a/Documentation/devicetree/bindings/mmc/meson-mmc.txt b/Documentation/devicetree/bindings/mmc/meson-mmc.txt
new file mode 100644
index 0000000..328157e
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/meson-mmc.txt

@@ -0,0 +1,30 @@
+* Amlogic Meson MMC controller
+
+The highspeed MMC host controller on Amlogic SoCs provides an interface
+for MMC, SD, SDIO and SDHC types of memory cards.
+
+Supported maximum speeds are the ones of the eMMC standard 4.41 as well
+as the speed of SD standard 2.0.
+
+Required properties:
+ - compatible : "amlogic,meson-mmc"
+ - reg : mmc controller base registers
+ - interrupts : mmc controller interrupt
+ - clocks : phandle to clock provider
+ - pinctrl-names : should contain "sdio_a" or "sdio_b"
+ - pinctrl-0: Should specify pin control groups used for this controller
+
+Optional properties:
+ - meson,sd-port : 0 for port A, 1 for port B

This is different than the pinctrl-names? It needs a better description
including what is the default if absent.

This was already discussed here
http://www.spinics.net/lists/linux-mmc/msg34407.html.
In the previous version (V4) I used pinctrl-names to select the
correct port but discussing with Ulf we decided to switch back to have
a new property in the DTS.
About what this value is, it is a bit up to our interpretation. We use
this value to setup the SDIO_PORT_SEL register and in the register
description in the documentation I read only "SDIO port selection. 0:
SDIO A; 1: SDIO B".
So I'm assuming this is somehow related to the muxing / pin controller
configuration but probably it's better to stay on the safe side and
just have a new property to setup this value.

I'll add the new default value in the next version.

-- 
Carlo Caione