在 2026/10/30 下午6:10, Thomas Zimmermann 写道:
Hi
Am 30.10.26 um 09:39 schrieb zhaotianrui:
在 2026/10/30 下午4:17, Thomas Zimmermann 写道:
Hi
Am 30.10.26 um 08:04 schrieb zhaotianrui:
在 2026/10/29 下午4:16, Thomas Zimmermann 写道:
Hi
Am 29.10.26 um 02:36 schrieb Tianrui Zhao:
LoongArch systems with hybrid graphics (integrated +
discrete GPU) can benefit from the same GPU switching
mechanism that x86 laptops use. Relax the dependency
to allow VGA_SWITCHEROO to be built on LoongArch,
consistent with the existing dependencies on ACPI,
PCI, and FB=y.
Change-Id: I84d38fdfe5e1591495fb3681474a7f1f64281fa8
Internal change ids should be remove before submitting patches.
Thanks for your review, I will fix this.
Best regards
Tianrui Zhao
Signed-off-by: Tianrui Zhao <[email protected]>
---
drivers/gpu/vga/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
index bad4bcee313..89edd1211aa 100644
--- a/drivers/gpu/vga/Kconfig
+++ b/drivers/gpu/vga/Kconfig
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0-only
config VGA_SWITCHEROO
bool "Laptop Hybrid Graphics - GPU switching support"
- depends on X86
+ depends on X86 || LOONGARCH
I'm a bit skeptical if that's all there is to do. Does loongarch
really work with the existing handlers in the graphics drivers
as-is? See [1] for the interface that implements the actual
switching.
[1]
https://elixir.bootlin.com/linux/v7.3/source/include/linux/vga_switcheroo.h#L93
Best regards
Thomas
Thanks, I will carefully check whether all these
vga_switcheroo_handler callbacks are supported on the LoongArch
platform.
Switcheroo used to be required for x86 notebooks from ~2010. Those
systems had two graphics cards, but only one set of output
connectors. That design is become rare, I think.
So I'm a bit surprised to see it come back. Which loongarch systems
are there?
Best regards
Thomas
Hi Thomas,
Thanks for your reply.
On the Loongson platform, we don't have the "two GPUs but only one
set of display outputs" scenario you described. However, we do have
systems where an integrated GPU and a discrete GPU coexist.
We would like to use the vga_switcheroo interface to switch between
the discrete GPU (DIS) and the integrated GPU (IGD), and to configure
the default VGA device.
Would this approach be feasible? Do you have any suggestions or
recommendations?
Oh, that's not what vga_switcheroo is for. For your scenario, simply
provide a DRM driver for each GPU. Selection of the boot-up display
happens in the UEFI/BIOS. Picking the correct display hardware at
runtime is left to clients in user space (or fbcon). DRM itself has
not preference.
Hi Thomas,
Thanks for the correction. We will provide a DRM driver per GPU and let
UEFI/BIOS to select boot vga device. If loongson platform has such a
display model int the future, we can then reconsider to support
vga_switcheroo.
Best regards
Tianrui Zhao
Best regards
Thomas
Best regards
Tianrui Zhao
Best regards
Tianrui Zhao
depends on ACPI
depends on PCI
depends on FB=y
