[U-Boot] [PATCH v5 011/101] fdt: Show the preprocessed .dts file on error

[Bin Meng]

Hi Simon,

On Mon, Nov 25, 2019 at 12:11 PM Simon Glass <sjg at chromium.org> wrote:
>
> When device-tree compilation fails it is sometimes tricky to see which
> line is broken, since the input file to dtc is a pre-processed version
> of the device tree.
>
> Add a line that points to the file that needs to be checked:
>
> When the error is in the main .dts file, output is something like this:
>
>    output: 'Error: arch/x86/dts/.chromebook_coral.dtb.pre.tmp:478.46-47
>         syntax error
>    FATAL ERROR: Unable to parse input tree
>
> but in fact looking at that file shows nothing useful:
>
>    PAD_CFG_NF_IOSSTATE_IOSTERM(GPIO_157, UP_20K, DEEP, NF1, HIZCRX1, DISPUPD)
>
> Instead we need to look at the preprocessed file, which shows:
>
>    163 ((1U << 30) | (1 << 10)) ((0xb << 10) | PAD_CFG1_IOSSTATE_HIZCRX1)
>
> Here it is clear that PAD_CFG1_IOSSTATE_HIZCRX1 is not defined and so is
> not being resolved by the preprocessor.
>
> This commit adds an additional useful message:
>
>    Check arch/x86/dts/.chromebook_coral.dtb.dts.tmp for errors
>
> Note that if the error is reported in an included file, such as
> u-boot.dtsi then the output is the following:
>
>    Error: arch/x86/dts/u-boot.dtsi:137.14-15 syntax error
>    FATAL ERROR: Unable to parse input tree
>
> But again, if the error is due to a preprocessor failure, like this:
>
>    filename = CONFIG_IFW_INPUT_FILE;
>
> then you can't tell what the problem is by looking at the source. All you
> see is the original code:
>
>         intel-ifwi {
>                 filename = CONFIG_IFW_INPUT_FILE;
>                 ...
>                 };
>         };
>         intel-fsp-m {
>                 filename = CONFIG_FSP_FILE_M;
>         };
>
> Everything looks fine. But looking at the output of the preprocessor:
>
>  intel-ifwi {
>   filename = CONFIG_IFW_INPUT_FILE;
>   ...
>  };
>  intel-fsp-m {
>   filename = "fsp_m.bin";
>  };
>
> This shows that the filename (normally "fitimage.bin") has not been
> inserted the preprocess, leading to the realisation that the value should
> be CONFIG_IFWI_INPUT_FILE.
>
> If the above does not make sense, I encourage people to try introducing
> errors in the device tree preprocessed values.
>

This makes sense now. Thanks for the detailed description. It helps
people understand what the real problem is.

> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v5: None
> Changes in v4:
> - One last desperate attempt to try to explain the purpose of this commit
> - Update the message to mention the preprocessed file, not un-preprocessed
>
> Changes in v3:
> - Update example error message to better show the intended purpose
>
> Changes in v2: None
>
>  scripts/Makefile.lib | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>

Regards,
Bin