Re: [PATCH v4] ACPI: Fix acpi_evaluate_object() return value check

[Bjorn Helgaas]

On Mon, Jan 20, 2014 at 7:46 PM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote:
> Since acpi_evaluate_object() returns acpi_status and not plain int,
> ACPI_FAILURE() should be used for checking its return value.
>
> Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> ---
> v3->v4: Fix spell error, add Jani Nikula reviewed-by.
> v2->v3: Fix compile error pointed out by Hanjun.
> v1->v2: Add CC to related subsystem MAINTAINERS
> ---
>  drivers/gpu/drm/i915/intel_acpi.c              |   24 ++++++++++++++----------
>  drivers/gpu/drm/nouveau/core/subdev/mxm/base.c |    9 +++++----
>  drivers/gpu/drm/nouveau/nouveau_acpi.c         |   23 +++++++++++++----------
>  drivers/pci/pci-label.c                        |    9 ++++++---

For the drivers/pci/pci-label.c part,

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

> +       status = acpi_evaluate_object(handle, "_DSM", &input, &output);
> +       if (ACPI_FAILURE(status)) {
> +               DRM_DEBUG_DRIVER("failed to evaluate _DSM: %s\n",
> +                               acpi_format_exception(status));

It's too bad there isn't an easy way to produce more informative error
messages, e.g., by including a namespace path or something.  A message
like:

    failed to evaluate _DSM: A requested entity is not found

is only useful if there's enough context to figure out what's going on.

Bjorn
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