https://bugs.kde.org/show_bug.cgi?id=502844
Bug ID: 502844
Summary: DMABUF format NV12 not advertised with NVIDIA card
Classification: Plasma
Product: kwin
Version: 6.3.3
Platform: Manjaro
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: kloz...@outlook.com
Target Milestone: ---
by checking info center, there's only one NV12 format with LINEAR modifier,
which doesn't work for me.
i checked the EGL api with GBM platform for DMABUF formats with NVIDIA
proprietary driver, some supported formats are shown as follows
```
format: NV12(3231564e), modifier: 3000000004fe010, external_only: true
format: NV12(3231564e), modifier: 3000000004fe011, external_only: true
format: NV12(3231564e), modifier: 3000000004fe012, external_only: true
format: NV12(3231564e), modifier: 3000000004fe013, external_only: true
format: NV12(3231564e), modifier: 3000000004fe014, external_only: true
format: NV12(3231564e), modifier: 3000000004fe015, external_only: true
format: NV12(3231564e), modifier: 0, external_only: true
format: R8 (20203852), modifier: 3000000004fe010, external_only: false
format: R8 (20203852), modifier: 3000000004fe011, external_only: false
format: R8 (20203852), modifier: 3000000004fe012, external_only: false
format: R8 (20203852), modifier: 3000000004fe013, external_only: false
format: R8 (20203852), modifier: 3000000004fe014, external_only: false
format: R8 (20203852), modifier: 3000000004fe015, external_only: false
format: R8 (20203852), modifier: 0, external_only: true
format: RG88(38384752), modifier: 3000000004fe010, external_only: false
format: RG88(38384752), modifier: 3000000004fe011, external_only: false
format: RG88(38384752), modifier: 3000000004fe012, external_only: false
format: RG88(38384752), modifier: 3000000004fe013, external_only: false
format: RG88(38384752), modifier: 3000000004fe014, external_only: false
format: RG88(38384752), modifier: 3000000004fe015, external_only: false
format: RG88(38384752), modifier: 0, external_only: true
```
kwin has special treatment for NV12, at src/utils/drm_format_helper.h:35, that
trying to convert NV12 to R8 and GR88, while the driver only support R8 and
RG88 on my setup.
```
static const QHash<uint32_t, YuvConversion> s_drmConversions = {
{DRM_FORMAT_NV12, YuvConversion{
{YuvFormat{DRM_FORMAT_R8, 1, 1},
YuvFormat{DRM_FORMAT_GR88, 2, 2}},
}},
};
```
i believe kwin removes NV12 modifiers at
src/platformsupport/scenes/opengl/abstract_egl_backend.cpp:142, by removing all
modifiers that not present in R8 and GR88, so it removes all modifiers since
GR88 not exists at all.
related [merge
request](https://invent.kde.org/plasma/kwin/-/merge_requests/4581)
i compiled kwin with GR88 replaced by RG88, then NV12 shows at info center,
though i don't know if it's the proper solution.
i can confirm it works by using mpv with dmabuf-wayland, and a modified
nvidia-vaapi-driver.
SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2
Kernel Version: 6.14.0-1-MANJARO (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-7700HQ CPU @ 2.80GHz
Memory: 23.4 GiB of RAM
Graphics Processor 1: NVIDIA GeForce GTX 1050/PCIe/SSE2
Graphics Processor 2: NVIDIA GeForce GTX 1050/PCIe/SSE2
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