On Wed, Apr 29, 2015 at 11:34 AM, Lee Jones <lee.jo...@linaro.org> wrote: > On Wed, 29 Apr 2015, Andrew Bresticker wrote: > >> Lee, >> >> On Wed, Apr 29, 2015 at 2:25 AM, Lee Jones <lee.jo...@linaro.org> wrote: >> > On Mon, 27 Apr 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 <abres...@chromium.org> >> >> Cc: Rob Herring <robh...@kernel.org> >> >> Cc: Pawel Moll <pawel.m...@arm.com> >> >> Cc: Mark Rutland <mark.rutl...@arm.com> >> >> Cc: Ian Campbell <ijc+devicet...@hellion.org.uk> >> >> Cc: Kumar Gala <ga...@codeaurora.org> >> >> Cc: Samuel Ortiz <sa...@linux.intel.com> >> >> Cc: Lee Jones <lee.jo...@linaro.org> >> >> --- >> >> New for v7. >> >> --- >> >> .../bindings/mfd/nvidia,tegra124-xusb.txt | 46 >> >> ++++++++++++++++++++++ >> >> 1 file changed, 46 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..6a46680 >> >> --- /dev/null >> >> +++ b/Documentation/devicetree/bindings/mfd/nvidia,tegra124-xusb.txt >> >> @@ -0,0 +1,46 @@ >> >> +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,<chip>-xusb", "nvidia,tegra124-xusb"' >> >> + where <chip> is tegra132. >> > >> > Okay. Why? >> >> Why what? This is the convention used for Tegra bindings and is also >> documented in Documentation/devicetree/bindings/submitting-patches.txt. >> See nvidia,tegra114-spi.txt and nvidia,tegra20-i2c.txt for other >> examples of this. > > It seems strange to me that you'd mention two specific chips in one > compatible string. What's the purpose of that?
The Tegra maintainers can correct me if I'm wrong here, but the point is, I think, to future-proof the binding. There are currently no differences between Tegra124 and Tegra132 that need to be accounted for in the driver, so the driver need only match against "nvidia,tegra124-xusb". If a Tegra132-specific quirk comes about later all Tegra132 device-trees will also include the "nvidia,tegra132-*" compatible string, so we can simply update the driver without breaking DT backwards-compatibility. >> >> + - reg: Must contain register base and length for each register set >> >> listed >> >> + in reg-names. >> > >> > You've mentioned 2 of the cells, what about the remaining 2? >> >> The example given was for Tegra124, where there are two address cells >> and two size cells. > > I don't get that. How does that work? Tegra124 has a physical address space of > 4GB because of LPAE, thus a single cell each for address and size is not sufficient. The arm64 Tegra SoCs will obviously also use two address and size cells. Take a look at arch/arm/boot/dts/tegra124.dtsi. -Andrew -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
