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References: <20230526091052.2169044-1-kherbst@redhat.com>
In-Reply-To: <20230526091052.2169044-1-kherbst@redhat.com>
From:   Ben Skeggs <skeggsb@gmail.com>
Date:   Thu, 13 Jul 2023 06:39:59 +1000
Message-ID: <CACAvsv7aGU0nkj-_HuGHFcX0STLNYHU5vHtnrrnfJvJqo=d-_w@mail.gmail.com>
Subject: Re: [Nouveau] [PATCH v2] drm/nouveau: bring back blit subchannel for
 pre nv50 GPUs
To:     Karol Herbst <kherbst@redhat.com>
Cc:     linux-kernel@vger.kernel.org, nouveau@lists.freedesktop.org,
        Ben Skeggs <bskeggs@redhat.com>,
        dri-devel@lists.freedesktop.org
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On Fri, 26 May 2023 at 19:11, Karol Herbst <kherbst@redhat.com> wrote:
>
> 1ba6113a90a0 removed a lot of the kernel GPU channel, but method 0x128
> was important as otherwise the GPU spams us with `CACHE_ERROR` messages.
>
> We use the blit subchannel inside our vblank handling, so we should keep
> at least this part.
>
> v2: Only do it for NV11+ GPUs
>
> Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/201
> Fixes: 4a16dd9d18a0 ("drm/nouveau/kms: switch to drm fbdev helpers")
> Signed-off-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>

> ---
>  drivers/gpu/drm/nouveau/nouveau_chan.c |  1 +
>  drivers/gpu/drm/nouveau/nouveau_chan.h |  1 +
>  drivers/gpu/drm/nouveau/nouveau_drm.c  | 20 +++++++++++++++++---
>  3 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c
> index e648ecd0c1a0..3dfbc374478e 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_chan.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_chan.c
> @@ -90,6 +90,7 @@ nouveau_channel_del(struct nouveau_channel **pchan)
>                 if (cli)
>                         nouveau_svmm_part(chan->vmm->svmm, chan->inst);
>
> +               nvif_object_dtor(&chan->blit);
>                 nvif_object_dtor(&chan->nvsw);
>                 nvif_object_dtor(&chan->gart);
>                 nvif_object_dtor(&chan->vram);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.h b/drivers/gpu/drm/nouveau/nouveau_chan.h
> index e06a8ffed31a..bad7466bd0d5 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_chan.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_chan.h
> @@ -53,6 +53,7 @@ struct nouveau_channel {
>         u32 user_put;
>
>         struct nvif_object user;
> +       struct nvif_object blit;
>
>         struct nvif_event kill;
>         atomic_t killed;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
> index cc7c5b4a05fd..9512f1c2f871 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -369,15 +369,29 @@ nouveau_accel_gr_init(struct nouveau_drm *drm)
>                 ret = nvif_object_ctor(&drm->channel->user, "drmNvsw",
>                                        NVDRM_NVSW, nouveau_abi16_swclass(drm),
>                                        NULL, 0, &drm->channel->nvsw);
> +
> +               if (ret == 0 && device->info.chipset >= 0x11) {
> +                       ret = nvif_object_ctor(&drm->channel->user, "drmBlit",
> +                                              0x005f, 0x009f,
> +                                              NULL, 0, &drm->channel->blit);
> +               }
> +
>                 if (ret == 0) {
>                         struct nvif_push *push = drm->channel->chan.push;
> -                       ret = PUSH_WAIT(push, 2);
> -                       if (ret == 0)
> +                       ret = PUSH_WAIT(push, 8);
> +                       if (ret == 0) {
> +                               if (device->info.chipset >= 0x11) {
> +                                       PUSH_NVSQ(push, NV05F, 0x0000, drm->channel->blit.handle);
> +                                       PUSH_NVSQ(push, NV09F, 0x0120, 0,
> +                                                              0x0124, 1,
> +                                                              0x0128, 2);
> +                               }
>                                 PUSH_NVSQ(push, NV_SW, 0x0000, drm->channel->nvsw.handle);
> +                       }
>                 }
>
>                 if (ret) {
> -                       NV_ERROR(drm, "failed to allocate sw class, %d\n", ret);
> +                       NV_ERROR(drm, "failed to allocate sw or blit class, %d\n", ret);
>                         nouveau_accel_gr_fini(drm);
>                         return;
>                 }
> --
> 2.40.1
>