Re: [RFC][PATCH] libdrm: gralloc_handle.h: Fix build issue with Android

[Stefan Schake <stschake@gmail.com>]

Hey John,

On Fri, Mar 16, 2018 at 10:48 PM, John Stultz <john.stultz@linaro.org> wrote:
> In trying to integrate the new gralloc_handle.h with the
> drm_hwcomposer, I started seeing the following compilation
> errors:
>
> In file included from external/drm_hwcomposer/platformdrmgeneric.cpp:28:
> external/libdrm/android/gralloc_handle.h:108:9: error: cannot initialize return object of type 'native_handle_t *' (aka 'native_handle *') with an lvalue of type 'struct gralloc_handle_t *'
>         return handle;
>                ^~~~~~
> 1 error generated.
>
> This seems to be due to the gralloc_handle_create() definition
> claiming to return a native_handle_t * type, rather then a
> gralloc_handle_t *, which is what the code actually returns.
>
> This function isn't actually used in the current drm_hwcomposer,
> so I'm not totally sure that this fix is correct (rather then
> returning the gralloc_handle_t's embadedded native_handle_t ptr).

This changed in 009634e49309 ("android: fix gralloc_handle_create() problems")
to make the return value from gralloc_handle_create opaque to its user.

Since the only one that would use gralloc_handle_create is the gralloc
implementation itself (and libdrm isn't one) and using getters/setters was
rejected (IIRC), I would think there is no reason to obscure the return type.
Since buffer_handle_t is native_handle_t* is gralloc_handle_t* it's also
correct. The alternative to changing the declaration here is returning
nhandle instead of handle.

Adding Rob Herring who authored 009634e49309.

Thanks,
Stefan
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