How to know the supported color formats about docs

[fooishbar]

There's no per-mode discovery since format and mode are usually independent. However you can look at the formats array in drmModePlaneInfo, or parse the IN_FORMATS plane-property blob. drm_info/Weston/etc are probably your best places to look at for this.

[dvdhrm]

The examples use dumb-buffers, which is the driver-agnostic way to drive the display. For those, I think nearly everyone assumes 32bit RGBX buffers are supported (I even thought that was a requirement to support the dumb-buffer-API).

I would assume that the supported color-formats are fixed for a given hardware+mode, and thus are not discoverable. However, I wouldn't be surprised if there are DRM-properties that you can query for this information. I honestly don't know, though. You can try checking the libgbm / libdrm / mesa codebase for details, or maybe @fooishbar knows more?

[dvdhrm]

Thanks a lot for the info! I think the IN_FORMATS is suitable for this!