Re: [PATCH v2] add a refresh_rate option to virtio-gpu

["Michael S. Tsirkin" <mst@redhat.com>]

>On Wed, Apr 15, 2026 at 12:19:05PM +0300, slonkazoid wrote:

Your From is mangled by qemu-devel (I'm not 100% sure when does it do
it, but it did here), so please include a From: line here inthe body.

And please add a short description here. Maybe the text below,
preferably with uppercase letters )


> Signed-off-by: slonkazoid <slonkazoid@slonk.ing>
> ---
> currently, the virtio-gpu module does not set a refresh rate, making it
> default to 75Hz in the qemu edid generation logic. i wrote a sloppy patch
> that adds a `refresh_rate` option to virtio-gpu, which propagates to all
> the devices based on it (i was interested in virtio-vga-gl). it's not of
> much use by itself but when combined with something like Sunshine or
> looking-glass, it can provide *far* smoother guest graphics than the
> inbuilt display devices. i have done a bare minimum amount of manual
> testing (virtio-vga-gl with venus XOR amdgpu drm native context streaming
> video games) and it functions as intended, and should not break the code
> path to fetch the refresh rate from the active display device (?), however,
> i have never contributed to QEMU before and i don't know the customs
> concerning testing, documentation, etc. if there's more i should do, please
> tell me! if this is something that would benefit QEMU, feel free to merge it.
> it's probably not a copyrightable change anyways.

I'm not sure why do you mention this? is there a copyright concern?

> ---
> Changes in v2:
> - Update default value of refresh_rate to the old implied default of 75000
> - Link to v1: https://lore.kernel.org/qemu-devel/20260414-virtio-gpu-refresh-rate-v1-1-59e6320eb24e@slonk.ing
> ---
>  hw/display/virtio-gpu-base.c   | 1 +
>  include/hw/virtio/virtio-gpu.h | 4 +++-
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/display/virtio-gpu-base.c b/hw/display/virtio-gpu-base.c
> index cb76302e2d..d87f6604d0 100644
> --- a/hw/display/virtio-gpu-base.c
> +++ b/hw/display/virtio-gpu-base.c
> @@ -232,6 +232,7 @@ virtio_gpu_base_device_realize(DeviceState *qdev,
>  
>      g->req_state[0].width = g->conf.xres;
>      g->req_state[0].height = g->conf.yres;
> +    g->req_state[0].refresh_rate = g->conf.refresh_rate;
>  
>      for (output_idx = 0, node = g->conf.outputs;
>           node && output_idx < g->conf.max_outputs;
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index f69fc19462..e440535fa0 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -131,6 +131,7 @@ struct virtio_gpu_base_conf {
>      uint32_t flags;
>      uint32_t xres;
>      uint32_t yres;
> +    uint32_t refresh_rate;
>      uint64_t hostmem;
>      VirtIOGPUOutputList *outputs;
>  };
> @@ -176,7 +177,8 @@ struct VirtIOGPUBaseClass {
>      DEFINE_PROP_BIT("edid", _state, _conf.flags, \
>                      VIRTIO_GPU_FLAG_EDID_ENABLED, true), \
>      DEFINE_PROP_UINT32("xres", _state, _conf.xres, 1280), \
> -    DEFINE_PROP_UINT32("yres", _state, _conf.yres, 800)
> +    DEFINE_PROP_UINT32("yres", _state, _conf.yres, 800), \
> +    DEFINE_PROP_UINT32("refresh_rate", _state, _conf.refresh_rate, 75000)
>  
>  typedef struct VGPUDMABuf {
>      QemuDmaBuf *buf;
> 
> ---
> base-commit: 985062e2319e6bf4a4be9c216ede6d34379e5777
> change-id: 20260414-virtio-gpu-refresh-rate-37b388e7dd72
> 
> Best regards,
> -- 
> slonkazoid <slonkazoid@slonk.ing>