As it turns out: while Nvidia does actually have interlacing knobs on their
GPU still pretty much no current GPUs since Volta actually support it.
Trying interlacing on these GPUs will result in NVDisplay being quite
unhappy like so:

nouveau 0000:1f:00.0: disp: chid 0 stat 00004802 reason 4 [INVALID_ARG] mthd 2008 data 00000001 code 00080000
nouveau 0000:1f:00.0: disp: chid 0 stat 10005080 reason 5 [INVALID_STATE] mthd 0200 data 00000001 code 00000001

So let's fix this by following the same behavior Nvidia's driver does and
disable interlacing entirely.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 43a9d1e1cf71..8100c75ee731 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -504,7 +504,8 @@ nouveau_connector_set_encoder(struct drm_connector *connector,
 			connector->interlace_allowed =
 				nv_encoder->caps.dp_interlace;
 		else
-			connector->interlace_allowed = true;
+			connector->interlace_allowed =
+				drm->client.device.info.family < NV_DEVICE_INFO_V0_VOLTA;
 		connector->doublescan_allowed = true;
 	} else
 	if (nv_encoder->dcb->type == DCB_OUTPUT_LVDS ||
-- 
2.37.1

On Tue, Aug 16, 2022 at 8:04 PM Lyude Paul <lyude@redhat.com> wrote:
>
> As it turns out: while Nvidia does actually have interlacing knobs on their
> GPU still pretty much no current GPUs since Volta actually support it.
> Trying interlacing on these GPUs will result in NVDisplay being quite
> unhappy like so:
>
> nouveau 0000:1f:00.0: disp: chid 0 stat 00004802 reason 4 [INVALID_ARG] mthd 2008 data 00000001 code 00080000
> nouveau 0000:1f:00.0: disp: chid 0 stat 10005080 reason 5 [INVALID_STATE] mthd 0200 data 00000001 code 00000001
>
> So let's fix this by following the same behavior Nvidia's driver does and
> disable interlacing entirely.
>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/gpu/drm/nouveau/nouveau_connector.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
> index 43a9d1e1cf71..8100c75ee731 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> @@ -504,7 +504,8 @@ nouveau_connector_set_encoder(struct drm_connector *connector,
>                         connector->interlace_allowed =
>                                 nv_encoder->caps.dp_interlace;
>                 else
> -                       connector->interlace_allowed = true;
> +                       connector->interlace_allowed =
> +                               drm->client.device.info.family < NV_DEVICE_INFO_V0_VOLTA;
>                 connector->doublescan_allowed = true;
>         } else
>         if (nv_encoder->dcb->type == DCB_OUTPUT_LVDS ||
> --
> 2.37.1
>

Reviewed-by: Karol Herbst <kherbst@redhat.com>