Documentation/process/maintainer-soc.rst

1 .. SPDX-License-Identifier: GPL-2.0
8 --------
10 The SoC subsystem is a place of aggregation for SoC-specific code.
13 * devicetrees for 32- & 64-bit ARM and RISC-V
14 * 32-bit ARM board files (arch/arm/mach*)
15 * 32- & 64-bit ARM defconfigs
16 * SoC-specific drivers across architectures, in particular for 32- & 64-bit
17   ARM, RISC-V and Loongarch
19 These "SoC-specific drivers" do not include clock, GPIO etc drivers that have
20 other top-level maintainers. The drivers/soc/ directory is generally meant
21 for kernel-internal drivers that are used by other drivers to provide SoC-
25 The SoC subsystem also serves as an intermediate location for changes to
33 Clearly this is quite a wide range of topics, which no one person, or even
35 is comprised of many submaintainers, each taking care of individual platforms
37 In this regard, "platform" usually refers to a series of SoCs from a given
38 vendor, for example, Nvidia's series of Tegra SoCs.  Many submaintainers operate
45 sending pull requests to the main SoC tree.  These trees are usually, but not
47 alias soc@kernel.org if there is no platform-specific maintainer, or if they
50 What the SoC tree is not, however, is a location for architecture-specific code
55 ------------------------------------
58 many of whom work for the silicon vendor, and may not be familiar with the
64 Perhaps one of the most important things to highlight is that dt-bindings
68 If changes are being made to a devicetree that are incompatible with old
83 corresponding change to the devicetree binding description, to ensure they are
86 missing additions to a header file in include/dt-bindings/, it will fail the
89 There are multiple ways to deal with this:
91 * Avoid defining custom macros in include/dt-bindings/ for hardware constants
92   that can be derived from a datasheet -- binding macros in header files should
93   only be used as a last resort if there is no natural way to define a binding
96   header is required, and change them to the named representation in a
99 * Defer the devicetree changes to a release after the binding and driver have
114 from board to board, are described in $soc-$board.dts.  An example of this is
115 jh7100-beaglev-starlight.dts.  Often many boards are variations on a theme, and
116 frequently there are intermediate files, such as jh7100-common.dtsi, which sit
117 between the $soc.dtsi and $soc-$board.dts files, containing the descriptions of
121 integrated into several different boards. For these platforms, $soc-$som.dtsi
122 and $soc-$som-$board.dts are typical.
125 inclusion, leading to some historical directory names in the tree.
130 ``make dtbs_check`` can be used to validate that devicetree files are compliant
131 with the dt-bindings that describe the ABI.  Please read the section
132 "Running checks" of Documentation/devicetree/bindings/writing-schema.rst for
135 For new platforms, or additions to existing ones, ``make dtbs_check`` should not
136 add any new warnings.  For RISC-V and Samsung SoC, ``make dtbs_check W=1`` is
137 required to not add any new warnings.
138 If in any doubt about a devicetree change, reach out to the devicetree
146 all be split into separate branches and appear in separate pull requests to the
150 Small sets of patches can also be sent as separate emails to soc@kernel.org,
154 top-level branches, e.g. for a treewide rework, or the addition of new SoC
159 SoC tree.  An example here would be one branch for devicetree warning fixes, one
160 for a rework and one for newly added boards.
162 Another common way to split up changes is to send an early pull request with the
163 majority of the changes at some point between rc1 and rc4, following up with one
167 While there is no cut-off time for late pull requests, it helps to only send
168 small branches as time gets closer to the merge window.
171 again having multiple smaller branches is better than trying to combine too many
172 patches into one pull request.
177 requests, please see Documentation/maintainer/pull-requests.rst.