Re: [PATCH] of: unittest: Statically apply overlays using fdtoverlay
From: David Gibson <hidden>
Date: 2021-01-18 06:52:28
Also in:
linux-kbuild, lkml
On Fri, Jan 15, 2021 at 11:14:50AM +0530, Viresh Kumar wrote:
+David, On 14-01-21, 09:01, Rob Herring wrote:quoted
On Wed, Jan 13, 2021 at 11:03 PM Viresh Kumar [off-list ref] wrote:quoted
On 11-01-21, 09:46, Rob Herring wrote:quoted
On Fri, Jan 8, 2021 at 2:41 AM Viresh Kumar [off-list ref] wrote:quoted
Now that fdtoverlay is part of the kernel build, start using it to test the unitest overlays we have by applying them statically.Nice idea.quoted
The file overlay_base.dtb have symbols of its own and we need to apply overlay.dtb to overlay_base.dtb alone first to make it work, which gives us intermediate-overlay.dtb file.Okay? If restructuring things helps we should do that. Frank?Frank, do we want to do something about it ? Maybe make overlay_base.dts an dtsi and include it from testcases.dts like the other ones ?No, because overlay_base.dts is an overlay dt.
So.. I was confused for a bit here, because the overlay_base.dts
you're discussing is the one in the kernel tree, not the one in the
dtc tree.
The kernel file is confusing to me. It has the /plugin/ tag which
should be used for overlays, but the rest of the file looks like a
base tree rather than an overlay. There's even a comment saying "Base
device tree that overlays will be applied against". But it goes on to
talk about __fixups__ and __local__fixups__ which will never be
generated for a based tree.
Oh.. and then there's terminology confusion. dtc has had compile time
resolved overlays for a very long time. Those are usually .dtsi
files, and should generally not have /plugin/.
More recent is the support for run-time overlays - .dtbo output files,
which are usually generated from a .dts with /plugin/. They usually
should *not* have a "/ { ... } " stanza, since that indicates the base
portion of the tree.
What property of a file makes it an overlay ? Just the presence of /plugin/; ?
Yes and no. Generally that's how it should work , but it looks to me like the presence of /plugin/ there is just wrong. /plugin/ basically just activates some extra dtc features, though, so it is possible to "manually" construct a valid overlay without it.
David, we are talking about the overlay base[1] file here. The fdtoverlay tool fails to apply it to testcases.dts file (in the same directory) because none of its nodes have the __overlay__ label and the dtc routine overlay_merge() [2] skips them intentionally.
testcases.dts also has /plugin/ and again, it's not really clear if
that's right.
The point of /plugin/ is that it will automatically generate the
__overlay__ subnodes from dtc's &label { ... } or &{/path} { ... }
syntax, so you wouldn't expect to see __overlay__ in the source.
quoted hunk ↗ jump to hunk
quoted
I think we need an empty, minimal base.dtb to apply overlay_base.dtbo to.One way out is adding an (almost-empty) testcase-data-2 in testcases.dtb, that will make it work.quoted
And then fdtoverlay needs a fix to apply overlays to the root node?It isn't just root node I think, but any node for which the __overlay__ label isn't there. So this can make it all work if everyone is fine with it:diff --git a/drivers/of/unittest-data/overlay_base.dts b/drivers/of/unittest-data/overlay_base.dts index 99ab9d12d00b..59172c4c9e5a 100644 --- a/drivers/of/unittest-data/overlay_base.dts +++ b/drivers/of/unittest-data/overlay_base.dts@@ -11,8 +11,7 @@ * dtc will create nodes "/__symbols__" and "/__local_fixups__". */ -/ { - testcase-data-2 { + &overlay_base { #address-cells = <1>; #size-cells = <1>;@@ -89,5 +88,3 @@ retail_1: vending@50000 { }; }; -}; -diff --git a/drivers/of/unittest-data/testcases.dts b/drivers/of/unittest-data/testcases.dts index a85b5e1c381a..539dc7d9eddc 100644 --- a/drivers/of/unittest-data/testcases.dts +++ b/drivers/of/unittest-data/testcases.dts@@ -11,6 +11,11 @@ node-remove { }; }; }; + + overlay_base: testcase-data-2 { + #address-cells = <1>; + #size-cells = <1>; + }; -------------------------8<-------------------------And then we can do this to the Makefile over my changes. -------------------------8<-------------------------diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile index 9f3eb30b78f1..8cc23311b778 100644 --- a/drivers/of/unittest-data/Makefile +++ b/drivers/of/unittest-data/Makefile@@ -41,7 +41,6 @@ DTC_FLAGS_testcases += -Wno-interrupts_property # Apply all overlays (except overlay_bad_* as they are not supposed to apply and # fail build) statically with fdtoverlay -intermediate-overlay := overlay.dtb master := overlay_0.dtb overlay_1.dtb overlay_2.dtb \ overlay_3.dtb overlay_4.dtb overlay_5.dtb \ overlay_6.dtb overlay_7.dtb overlay_8.dtb \@@ -50,15 +49,12 @@ master := overlay_0.dtb overlay_1.dtb overlay_2.dtb \ overlay_gpio_01.dtb overlay_gpio_02a.dtb \ overlay_gpio_02b.dtb overlay_gpio_03.dtb \ overlay_gpio_04a.dtb overlay_gpio_04b.dtb \ - intermediate-overlay.dtb + overlay_base.dtb overlay.dtb quiet_cmd_fdtoverlay = fdtoverlay $@ cmd_fdtoverlay = $(objtree)/scripts/dtc/fdtoverlay -o $@ -i $^ -$(obj)/intermediate-overlay.dtb: $(obj)/overlay_base.dtb $(addprefix $(obj)/,$(intermediate-overlay)) - $(call if_changed,fdtoverlay) - $(obj)/master.dtb: $(obj)/testcases.dtb $(addprefix $(obj)/,$(master)) $(call if_changed,fdtoverlay) -always-$(CONFIG_OF_OVERLAY) += intermediate-overlay.dtb master.dtb +always-$(CONFIG_OF_OVERLAY) += master.dtb
-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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