linux-kernel - Re: dtc issue with overlays starting in next-20171009

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Message-ID: <CAL_Jsq+f4Y1DDB4ZkXAEKUZ_P9YdMUKMhr2E=VKtbHWMZFaO0w@mail.gmail.com>
Date:   Wed, 18 Oct 2017 15:16:34 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Alan Tull <atull@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-fpga@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Devicetree Compiler <devicetree-compiler@...r.kernel.org>
Subject: Re: dtc issue with overlays starting in next-20171009

Use devicetree-compiler list for dtc issues please.

On Wed, Oct 18, 2017 at 2:33 PM, Frank Rowand <frowand.list@...il.com> wrote:
> Hi Rob, Alan,
>
> On 10/18/17 08:58, Alan Tull wrote:
>> Hi Rob,
>>
>> I've noticed a problem compiling DT overlays and traced it back to
>> beginning in next-20171009
>>
>> That tag adds the following in scripts/dtc
>>
>> e9480c1 2017-10-09 16:17:32 +0100 : Mark Brown : Merge remote-tracking
>> branch 'devicetree/for-next'
>> 4201d05 2017-10-03 15:03:47 -0500 : Rob Herring : scripts/dtc: Update
>> to upstream version v1.4.5-3-gb1a60033c110
>> 4322323 2017-10-03 15:03:46 -0500 : Rob Herring : scripts/dtc: add
>> fdt_overlay.c and fdt_addresses.c to sync script
>>
>> The error is:
>>
>> dtc: /home/atull/repos/linux-socfpga/scripts/dtc/livetree.c:543:
>> get_node_by_phandle: Assertion `(phandle != 0) && (phandle != -1)'
>> failed.
>> arch/arm/boot/dts/socfpga_overlay.dtb: Warning (clocks_property):
>> Could not get phandle node for
>> /fragment@..._overlay__/gpio@...40:clocks(cell 0)
>> Aborted (core dumped)
>> scripts/Makefile.lib:316: recipe for target
>> 'arch/arm/boot/dts/socfpga_arria10_socdk_sdmmc_ghrd_ovl_ext_cfg.dtb'
>> failed
>> make[2]: *** [arch/arm/boot/dts/socfpga_arria10_socdk_sdmmc_ghrd_ovl_ext_cfg.dtb]
>> Error 134
>> arch/arm/Makefile:346: recipe for target 'dtbs' failed
>>
>> Here's a simplified overlay that gets this error.  Taking out the line
>> "interrupt-parent = <&intc>;" fixes the build.
>>
>> /dts-v1/;
>> /plugin/;
>> / {
>>         fragment@0 {
>>                 target-path = "/soc/base_fpga_region";
>>                 #address-cells = <1>;
>>                 #size-cells = <1>;
>>
>>                 __overlay__ {
>>                         ranges = <0x00000000 0x00000000 0xc0000000 0x00040000>,
>>                                  <0x00000001 0x00000000 0xff200000 0x00001000>;
>>
>>                         external-fpga-config;
>>
>>                         #address-cells = <2>;
>>                         #size-cells = <1>;
>>
>>                         fpga_pr_region0 {
>>                                 compatible = "fpga-region";
>>                                 fpga-bridges = <&freeze_controller_0>;
>>                                 ranges;
>>                         };
>>
>>                         freeze_controller_0: freeze_controller@...00000450 {
>>                                 compatible = "altr,freeze-bridge-controller";
>>                                 reg = <0x00000001 0x00000450 0x00000010>;
>>                                 interrupt-parent = <&intc>;  /* <--
>> remove to fix build */
>>                                 interrupts = <0 21 4>;
>>                         };
>>                 };
>>         };
>> };
>>
>> Alan
>
> Phandle references in overlays are assigned the value of -1 (0xffffffff) in
> the dtb, to be fixed up when loaded.  A new check sees this value and
> triggers the assert.
>
> It is this commit in the upstream dtc tools tree:
>
>    commit ee3d26f6960bb5922d9a35fe266d9eac74a78ec0
>    checks: add interrupts property check
>
> There are a bunch of other new checks that call get_node_by_phandle(),
> and thus could trigger the assertion.
>
> I'm guessing that those checks would also trigger the assert if an
> overlay contained something that would lead to one of the other checks
> being processed.

You won't get an assert because I check for 0 or -1 and skip the check
in those cases. The interrupts check missed that condition.

However, as shown above, you will get an erroneous warning because it
just skips 1 cell and goes to the next to handle the case where the
phandle is optional and you want a fixed number of elements.

I guess we can't validate overlays which is unfortunate. I don't think
that's a solvable problem unless you have the base DT.

> You can avoid the problem in your example dts with "-Wno-interrupts_property"
>
>   dtc -Wno-interrupts_property fpga_01_a.dts
>
> The larger set of other checks that might trigger the assert is too large
> for me to want to add "-Wno-" flags for all of them to the command line
> (as temporary workarounds).

David thought more switches were better.

Rob