From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755692AbbESSgL (ORCPT ); Tue, 19 May 2015 14:36:11 -0400 Received: from mail-qk0-f174.google.com ([209.85.220.174]:33236 "EHLO mail-qk0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751669AbbESSgH (ORCPT ); Tue, 19 May 2015 14:36:07 -0400 MIME-Version: 1.0 In-Reply-To: References: <1430761002-9327-1-git-send-email-abrestic@chromium.org> <1430761002-9327-5-git-send-email-abrestic@chromium.org> <20150513143954.GA3394@x1> <55544CC5.9050001@nvidia.com> <20150514074058.GA22418@x1> Date: Tue, 19 May 2015 11:36:05 -0700 X-Google-Sender-Auth: A9VFXYhCoDZ1bO_PJxpVQKk4sks Message-ID: Subject: Re: [PATCH v8 4/9] mfd: Add binding document for NVIDIA Tegra XUSB From: Andrew Bresticker To: Lee Jones Cc: Jon Hunter , Stephen Warren , Thierry Reding , Alexandre Courbot , "devicetree@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Samuel Ortiz Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Lee, On Thu, May 14, 2015 at 10:38 AM, Andrew Bresticker wrote: > On Thu, May 14, 2015 at 12:40 AM, Lee Jones wrote: >> On Thu, 14 May 2015, Jon Hunter wrote: >> >>> Hi Lee, >>> >>> On 13/05/15 15:39, Lee Jones wrote: >>> > On Mon, 04 May 2015, Andrew Bresticker wrote: >>> > >>> >> Add a binding document for the XUSB host complex on NVIDIA Tegra124 >>> >> and later SoCs. The XUSB host complex includes a mailbox for >>> >> communication with the XUSB micro-controller and an xHCI host-controller. >>> >> >>> >> Signed-off-by: Andrew Bresticker >>> >> Cc: Rob Herring >>> >> Cc: Pawel Moll >>> >> Cc: Mark Rutland >>> >> Cc: Ian Campbell >>> >> Cc: Kumar Gala >>> >> Cc: Samuel Ortiz >>> >> Cc: Lee Jones >>> >> --- >>> >> Changes from v7: >>> >> - Move non-shared resources into child nodes. >>> >> New for v7. >>> >> --- >>> >> .../bindings/mfd/nvidia,tegra124-xusb.txt | 37 ++++++++++++++++++++++ >>> >> 1 file changed, 37 insertions(+) >>> >> create mode 100644 Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt >>> >> >>> >> diff --git a/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt b/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt >>> >> new file mode 100644 >>> >> index 0000000..bc50110 >>> >> --- /dev/null >>> >> +++ b/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt >>> >> @@ -0,0 +1,37 @@ >>> >> +NVIDIA Tegra XUSB host copmlex >>> >> +============================== >>> >> + >>> >> +The XUSB host complex on Tegra124 and later SoCs contains an xHCI host >>> >> +controller and a mailbox for communication with the XUSB micro-controller. >>> >> + >>> >> +Required properties: >>> >> +-------------------- >>> >> + - compatible: For Tegra124, must contain "nvidia,tegra124-xusb". >>> >> + Otherwise, must contain '"nvidia,-xusb", "nvidia,tegra124-xusb"' >>> >> + where is tegra132. >>> >> + - reg: Must contain the base and length of the XUSB FPCI registers. >>> >> + - ranges: Bus address mapping for the XUSB block. Can be empty since the >>> >> + mapping is 1:1. >>> >> + - #address-cells: Must be 2. >>> >> + - #size-cells: Must be 2. >>> >> + >>> >> +Example: >>> >> +-------- >>> >> + usb@0,70098000 { >>> >> + compatible = "nvidia,tegra124-xusb"; >>> >> + reg = <0x0 0x70098000 0x0 0x1000>; >>> >> + ranges; >>> >> + >>> >> + #address-cells = <2>; >>> >> + #size-cells = <2>; >>> >> + >>> >> + usb-host@0,70090000 { >>> >> + compatible = "nvidia,tegra124-xhci"; >>> >> + ... >>> >> + }; >>> >> + >>> >> + mailbox { >>> >> + compatible = "nvidia,tegra124-xusb-mbox"; >>> >> + ... >>> >> + }; >>> > >>> > This doesn't appear to be a proper MFD. I would have the USB and >>> > Mailbox devices probe seperately and use a phandle to point the USB >>> > device to its Mailbox. >>> > >>> > usb@xyz { >>> > mboxes = <&xusb-mailbox, [chan]>; >>> > }; >>> > >>> >>> I am assuming that Andrew had laid it out like this to reflect the hw >>> structure. The mailbox and xhci controller are part of the xusb >>> sub-system and hence appear as child nodes. My understanding is that for >>> device-tree we want the device-tree structure to reflect the actual hw. >>> Is this not the case? >> >> Yes, the DT files should reflect h/w. I have requested to see what >> the memory map looks like, so I might provide a more appropriate >> solution to accepting a pretty pointless MFD. > > FWIW, the address map for XUSB looks like this: > > XUSB_HOST: 0x70090000 - 0x7009a000 > xHCI registers: 0x70090000 - 0x70098000 > FPCI configuration registers: 0x70098000 - 0x70099000 > IPFS configuration registers: 0x70099000 - 0x7009a000 > >> Two solutions spring to mind. You can either call >> of_platform_populate() from the USB driver, as some already do: >> >> drivers/usb/dwc3/dwc3-exynos.c: >> ret = of_platform_populate(node, NULL, NULL, dev); >> drivers/usb/dwc3/dwc3-keystone.c: >> error = of_platform_populate(node, NULL, NULL, dev); >> drivers/usb/dwc3/dwc3-omap.c: >> ret = of_platform_populate(node, NULL, NULL, dev); >> drivers/usb/dwc3/dwc3-qcom.c: >> ret = of_platform_populate(node, NULL, NULL, qdwc->dev); >> drivers/usb/dwc3/dwc3-st.c: >> ret = of_platform_populate(node, NULL, NULL, dev); >> drivers/usb/musb/musb_am335x.c: >> ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev); > > This still requires a small, separate driver to setup the regmap and > do of_platform_populate(). The only difference is it lives in > drivers/usb/ instead of drivers/mfd/. > >> Or use the "simple-mfd", which is currently in -next: >> >> git show next/master:Documentation/devicetree/bindings/mfd/mfd.txt > > I'm not too opposed to this, but Thierry was when I brought this up > before. The issue here is that if we ever have to do something > besides setting up a regmap in the MFD, we'd have to change the > binding and break DT backwards-compatibility. Any thoughts on this? A minimal MFD seems to be the best way to future-proof this binding/driver should it need to be extended in the future. If this is a firm NAK from you however, I'll need to let Jassi now so that he can un-queue the mailbox patches for 4.2.... Thanks, Andrew