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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Golle <daniel@makrotopia.org>
Date: Tue, 26 May 2026 01:55:36 +0100
Subject: [PATCH] zink: allow KMS-only display fd to fall through to default
Vulkan device selection
When MESA_LOADER_DRIVER_OVERRIDE=zink is used with a GBM device created
on a KMS-only display node (e.g. /dev/dri/card1 bound to verisilicon-dc
on StarFive JH7110), zink_render_rdev() returned -1 because the device
has no render node, causing zink_drm_create_screen() to bail and GBM
initialisation to fail.
Treat the missing render node as "no specific device requested" instead
of an error. zink_picks_device() then returns false, and choose_pdev()
falls back to default Vulkan physical-device selection, picking
whichever ICD vkEnumeratePhysicalDevices() reports first (PowerVR on
JH7110). Cross-device dma-buf import via VK_KHR_external_memory_fd
takes care of getting the rendered frame onto the display controller.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
src/gallium/drivers/zink/zink_screen.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/src/gallium/drivers/zink/zink_screen.c
+++ b/src/gallium/drivers/zink/zink_screen.c
@@ -3882,10 +3882,15 @@ zink_render_rdev(int fd, int64_t *dev_ma
if (drmGetDevice2(fd, 0, &dev))
return -1;
- if(!(dev->available_nodes & (1 << DRM_NODE_RENDER))) {
- ret = -1;
+ /*
+ * If the fd points to a KMS-only display device with no render node,
+ * leave dev_major/dev_minor unset. choose_pdev() will then fall back
+ * to default Vulkan physical-device selection, allowing zink to drive
+ * a render-only GPU (e.g. PowerVR via VK_KHR_external_memory_fd) on
+ * top of a separate display controller (e.g. verisilicon-dc).
+ */
+ if(!(dev->available_nodes & (1 << DRM_NODE_RENDER)))
goto free_device;
- }
if(stat(dev->nodes[DRM_NODE_RENDER], &stx)) {
ret = -1;
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