[rcore][drm] `eglGetDisplay` fails on some platforms

[maiphi]

Issue description

On one of my boards with Mali-T764 and the proprietary Midgard driver, getting the EGL display connection with eglGetDisplay in rcore_drm.c fails.

The preferred way to get the connection is getPlatformDisplay instead.

I got this working and will send a pull request with the patch (after testing it on other systems).

Environment

An embedded board based on rk3288 and Mali-T764 with Yocto Scarthgap. Raylib built with PLATFORM=DRM and OpenGL ES 2.0.

(With the Panfrost driver, the issue does not occur. But with Panfrost, OpenGL hardware acceleration fails entirely on that platform, forcing software rendering.)

[raysan5]

@maiphi Do you mean eglGetPlatformDisplay()? In that case, it can be considered as an alternative call.

Otherwise, if it is a driver specific API call, I'm afraid platform_drm is intended for devices supporting standard EGL API calls. In the past, same happened with Raspberry Pi while using the propietary Broadcom driver, it required special Broadcam libraries and API calls but unfortunately it added lot of maintenance code and minimum portability.

[maiphi]

Do you mean eglGetPlatformDisplay()?

Sorry, copy & paste error.

In the linked code I'm using eglGetPlatformDisplayEXT which is available as an extension since EGL 1.4. Probably this will work with eglGetPlatformDisplay as well, which is available since EGL 1.5. I'll try that (it will take a week until I have the board again). Earlier versions can be supported with dynamic lookup (as in the commit above) and fallback to eglGetDisplay if necessary. All calls are in the official standard.

As I understand it, eglGetDisplay is considered legacy API and should generally be replaced by eglGetPlatformDisplay.