Retroarch: Fast forward doesn't work with vulkan when run from a tty.

[orbea]

Description

When using fast forward with a kms context and vulkan it has zero impact.

It works with vulkan with X11 and opengl with kms.

Expected behavior

The fast forward feature should work normally with vulkan with kms.

Actual behavior

Fast forward with vulkan with a kms context has zero effect.

Steps to reproduce the bug

1. Start RetroArch with a kms context and vulkan.
2. Start any core + content (i.e. snes9x-libretro).
3. Toggle fast forward.

Bisect Results

N/A

Older RetroArch commits have other issues with kms and vulkan making a bisect not possible.

Version/Commit

You can find this information under Information/System Information

• RetroArch: https://github.com/libretro/RetroArch/commit/b40aa13418facd23f7696b5d92c1b473534d884b

Environment information

• OS: Slackware64-current
• Compiler: gcc-8.3.0
• GPU: Radeon RX Vega 56
• mesa: https://github.com/mesa3d/mesa/commit/0aa5a97b03159f59513bd96dbf7c25c2d22e3c1c
• vulkan-sdk: 1.1.92.1
• linux: 4.20.12

[twinaphex]

What context are you talking about ? I don't believe we have a KMS context driver written for Vulkan, only VK_KHR_display?

[orbea]

You're right, its not KMS, I was mistaken. I mean when running RetroArch with vulkan from an unused tty.

[WARN] Failed to bind API (#9, version 1.0) on context driver "x-egl".
[WARN] Failed to bind API (#9, version 1.0) on context driver "kms".
[WARN] Failed to bind API (#9, version 1.0) on context driver "sdl_gl".
[INFO] Vulkan dynamic library loaded.
[INFO] [Vulkan]: Detecting screen resolution 0x0.
[INFO] [Vulkan]: Using GPU: AMD RADV VEGA10 (LLVM 7.0.1)
[INFO] [Vulkan]: Queue family 0 supports 1 sub-queues.
[INFO] [Vulkan]: Swapchain supports present mode: 2.
[INFO] [Vulkan]: Creating swapchain with present mode: 2
[INFO] [Vulkan]: Using swapchain size 1680 x 1050.
[INFO] [Vulkan]: Got 3 swapchain images.
[INFO] [Vulkan]: Using resolution 1680x1050
[INFO] [Vulkan]: Using RGB565 format.
[INFO] [Vulkan]: GPU supports linear images as textures, but not DEVICE_LOCAL. Falling back to copy path.
[INFO] [Vulkan]: GPU supports linear images as textures, but not DEVICE_LOCAL. Falling back to copy path.
[INFO] [Vulkan]: GPU supports linear images as textures, but not DEVICE_LOCAL. Falling back to copy path.
[INFO] [Vulkan]: Loading stock shader.
[INFO] [slang]: Building pass #0 (N/A)
[INFO] [slang]: Reflection
[INFO] [slang]:   Textures:
[INFO] [slang]:      Source (#0)
[INFO] [slang]:
[INFO] [slang]:   Uniforms (Vertex: yes, Fragment: no):
[INFO] [slang]:   Push Constants (Vertex: no, Fragment: no):
[INFO] [slang]:      MVP (Offset: 0)
[INFO] [slang]:
[INFO] [slang]:   Parameters:
[INFO] [Vulkan filter chain]: Not using frame history.
[INFO] [Vulkan filter chain]: Not using framebuffer feedback.

[hizzlekizzle]

IIRC, this is a known issue with mesa drivers, as they don't support the mailbox feature. Nvidia drivers can fast-forward normally, I believe.

[orbea]

What's the mailbox feature? Would this be true if fast forward works normally with a X11 context?

[hizzlekizzle]

You can read about it here:
http://themaister.net/blog/2018/07/02/improving-vk_khr_display-in-mesa-or-lets-make-drm-better/