Use gbm_bo_create_with_modifiers + don't encode if capture fails #220
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gbm_bo_create will return DRM_FORMAT_MOD_INVALID and that may not be importable on compositor side with some formats. Fallback to gbm_bo_create for GPUs without modifiers support.
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| buffer.bo = gbm_bo_create(gbm_device, buffer.width, | ||
| buffer.height, format, GBM_BO_USE_LINEAR | GBM_BO_USE_RENDERING); | ||
| const uint64_t modifier = 0; // DRM_FORMAT_MOD_LINEAR | ||
| buffer.bo = gbm_bo_create_with_modifiers(gbm_device, buffer.width, |
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Would you mind explaining why we try with_modifiers first, when should one use the two functions for allocation here?
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gbm_bo_create_with_modifiers is always preferable when supported (kernel supports modifiers). There are however still some GPUs without modifiers support, and with those the gbm_bo_create_with_modifiers will fail and we have to fallback to gbm_bo_create.
gbm_bo_create should work everywhere, but it will return DRM_FORMAT_MOD_INVALID which may be problematic - for example Vulkan doesn't allow importing dmabufs with invalid modifier.
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Aha, interesting. Do you happen to have a link to documentation explaining these things? My google-foo has failed me this time.
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I don't know of any documentation explaining this, sorry. Most of my understanding comes from studying code.
Similar logic in wlroots https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/master/render/allocator/gbm.c#L92
Actually the dmabuf screencopy code is based on wlroots example which uses gbm_bo_create only and up until now I didn't know it will always return invalid modifier. For some reason I expected it to return some (best?) modifier if kernel supports modifiers, and I didn't confirm it because it seemed to just work. Also gbm documentation doesn't mention it either.
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