Re: [PATCH] vga-switcheroo: Allow VGA_SWITCHEROO to be enabled on LoongArch

[Thomas Zimmermann <tzimmermann@suse.de>]

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 <zhaotianrui@loongson.cn>
>>> ---
>>>   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


>
>
> Best regards
>
> Tianrui Zhao
>
>>>       depends on ACPI
>>>       depends on PCI
>>>       depends on FB=y
>>
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)