Hi All, Arend asked me to test these 2 patches for adding devicetree support to brcmfmac sdio devices: "dt: bindings: add bindings for Broadcom bcm43xx sdio devices" "brcmfmac: add device tree support for SDIO devices" https://groups.google.com/forum/#!msg/linux-sunxi/Zph6zDTnAcw/_-wOO-gnIuQJ Getting this to do anything at all meant also adding this patch: "mmc: Add SDIO function devicetree subnode parsing" https://lkml.org/lkml/2014/4/3/522 So that the card / sdio-func devices would actually get their of_node pointer set to the child node under the mmc controller describing the sdio wifi module. But that does not solve the entire problem. Listing the oob-interrupt info in the child node works fine. But listing the brcm,wlan-supply gpio does not. Since these sdio wifi modules are typically soldered onto the board, there mmc controller device tree node has non-removable; set, so the mmc subsystem will try to initialize the sdio device as soon as the mmc driver loads, and if that fails will never look at it again. So we need to have the brcm,wlan-supply gpio driven high *before* the mmc host driver initializes. In case of the brcm,wlan-supply property, this is actually a problem which we've already solved in a number of dts files for allwinner boards, simply create a fixed-regulator with an enable/disable gpio, and set that as vmmc-supply for the mmc-host for the sdio wifi. However the "brcmfmac: add device tree support for SDIO devices" patch also adds support for 2 devicetree controlled clocks. Assuming these need to be ungated before the sdio module will respond to mmc commands, we have the same problem. I've been thinking a bit about this, and it is a non trivial problem since sdio devices are normally instantiated when probed, unlike ie spi devices which are instantiated from devicetree. Adding device tree instantiation of sdio devices seems like a bad idea, as then we get 2 vastly different device instantiation paths. Still we need some way to get power and clks setup before the mmc host initializes. Therefor I would like to suggest to add a number of standard properties to mmc-bus child nodes. Making the dts for an mmc host with an sdio device which needs clks setup before it will work look like this: mmc3: mmc@01c12000 { #address-cells = <1>; #size-cells = <0>; pinctrl-names = "default"; pinctrl-0 = <&mmc3_pins_a>; vmmc-supply = <®_vmmc3>; bus-width = <4>; non-removable; status = "okay"; brcmf: bcrmf@0 { reg = <0>; compatible = "brcm,bcm43xx-fmac"; clocks = <&clk_out_a>, <&clk_out_b>; clock-frequency = <32768>, <26000000>; interrupt-parent = <&pio>; interrupts = <10 4>; /* PH10 / EINT10 */ interrupt-names = "host-wake"; status = "okay"; }; }; Where the "clocks" and "clock-frequency" attributes would be something which we standardize in Documentation/devicetree/bindings/mmc/mmc-bus.txt These standard properties would *not* be used by the driver for the childnode device, so as to avoid the chicken and egg problem of that driver needing to enable clks, and it only getting bound to the device after the device has been discovered which requires those clocks. Instead these properties would be parsed by mmc_of_parse, and we will get enabled automatically by mmc_add_host before doing any probing. If the optional clock-frequency property is also set, then mmc_add_host will not only enable the clks but also set them to the specified frequency. Note I've no boards which actually need the clocks, all 3 boards with sdio wifi which I've use a 26MHz crystal directly attached to the module, so once I get the oob interrupt working (this needs some work on the allwinner side) we can merge Arend's patches with the clock bits dropped for now. Still I want to get a discussion going on this, so that when the time comes that we do need it we know how to deal with this, or ideally already have code in place to deal with it. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
