On Thu, May 5, 2016 at 9:39 AM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: > > On 03/05/16 19:22, Rob Herring wrote: >> On Fri, Apr 29, 2016 at 02:53:45PM +0100, Jon Hunter wrote: >>> Add binding documentation for the Tegra ACONNECT bus that is part of the >>> Audio Processing Engine (APE) on Tegra210. The ACONNECT bus is used to >>> access devices within the APE subsystem. The APE is located in a >>> separate power domain and so accesses made to the ACONNECT require the >>> power domain to be enabled as well as some platform specific clocks. >>> >>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx> >>> --- >>> .../bindings/bus/nvidia,tegra210-aconnect.txt | 45 ++++++++++++++++++++++ >>> 1 file changed, 45 insertions(+) >>> create mode 100644 Documentation/devicetree/bindings/bus/nvidia,tegra210-aconnect.txt >>> >>> diff --git a/Documentation/devicetree/bindings/bus/nvidia,tegra210-aconnect.txt b/Documentation/devicetree/bindings/bus/nvidia,tegra210-aconnect.txt >>> new file mode 100644 >>> index 000000000000..e5e915f8fca7 >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/bus/nvidia,tegra210-aconnect.txt >>> @@ -0,0 +1,45 @@ >>> +NVIDIA Tegra ACONNECT Bus >>> + >>> +The Tegra ACONNECT bus is an AXI switch which is used to connnect various >>> +components inside the Audio Processing Engine (APE). All CPU accesses to >>> +the APE subsystem go through the ACONNECT via an APB to AXI wrapper. >>> + >>> +Required properties: >>> +- compatible: Must be "nvidia,tegra210-aconnect". >>> +- clocks: Must contain the entries for the APE clock (TEGRA210_CLK_APE), >>> + and APE interface clock (TEGRA210_CLK_APB2APE). >>> +- clock-names: Must contain the names "ape" and "apb2ape" for the corresponding >>> + 'clocks' entries. >>> +- power-domains: Must contain a phandle that points to the audio powergate >>> + (namely 'aud') for Tegra210. >>> +- #address-cells: The number of cells used to represent physical base addresses >>> + in the host1x address space. Should be 2. >>> +- #size-cells: The number of cells used to represent the size of an address >>> + range in the host1x address space. Should be 2. >> >> Do you really need >4GB of child addresses? > > Sounds rather silly when you put it like that. No, its not needed. I > will fix that. > >>> +- ranges: 1:1 mapping of the aconnect address space to the CPU address space. >> >> Why 1:1 for 256KB of address space? > > No good reason. I have looking at what we did for host1x and ahub which > also have a ranges property and use a 1:1 mapping. For ahub this makes > sense because it is more of a cross-bar/switch. The aconnect bus is also > a switch and thought may be that is the easiest thing to do. What is > recommended here? Use of non-empty ranges is preferred though there is not much benefit if the parent and child sizes are the same. However, it does also limit what is a valid address for those child nodes. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
