[PATCH] drm/nouveau: fix dma syncing warning with debugging on.

[Lyude Paul]

Reviewed-by: Lyude Paul <lyude at redhat.com>

Let me know when this has been pushed somewhere

On Mon, 2021-02-01 at 11:01 +1000, Dave Airlie wrote:
> From: Dave Airlie <airlied at redhat.com>
> 
> Since I wrote the below patch if you run a debug kernel you can a
> dma debug warning like:
> nouveau 0000:1f:00.0: DMA-API: device driver tries to sync DMA memory it has
> not allocated [device address=0x000000016e012000] [size=4096 bytes]
> 
> The old nouveau code wasn't consolidate the pages like the ttm code,
> but the dma-debug expects the sync code to give it the same base/range
> pairs as the allocator.
> 
> Fix the nouveau sync code to consolidate pages before calling the
> sync code.
> 
> Fixes: bd549d35b4be0 ("nouveau: use ttm populate mapping functions. (v2)")
> Reported-by: Lyude Paul <lyude at redhat.com>
> Reviewed-by: Ben Skeggs <bskeggs at redhat.com>
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_bo.c | 35 +++++++++++++++++++++++-----
>  1 file changed, 29 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
> b/drivers/gpu/drm/nouveau/nouveau_bo.c
> index 33dc886d1d6d..2375711877cf 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
> @@ -547,7 +547,7 @@ nouveau_bo_sync_for_device(struct nouveau_bo *nvbo)
>  {
>         struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
>         struct ttm_tt *ttm_dma = (struct ttm_tt *)nvbo->bo.ttm;
> -       int i;
> +       int i, j;
>  
>         if (!ttm_dma)
>                 return;
> @@ -556,10 +556,21 @@ nouveau_bo_sync_for_device(struct nouveau_bo *nvbo)
>         if (nvbo->force_coherent)
>                 return;
>  
> -       for (i = 0; i < ttm_dma->num_pages; i++)
> +       for (i = 0; i < ttm_dma->num_pages; ++i) {
> +               struct page *p = ttm_dma->pages[i];
> +               size_t num_pages = 1;
> +
> +               for (j = i + 1; j < ttm_dma->num_pages; ++j) {
> +                       if (++p != ttm_dma->pages[j])
> +                               break;
> +
> +                       ++num_pages;
> +               }
>                 dma_sync_single_for_device(drm->dev->dev,
>                                            ttm_dma->dma_address[i],
> -                                          PAGE_SIZE, DMA_TO_DEVICE);
> +                                          num_pages * PAGE_SIZE,
> DMA_TO_DEVICE);
> +               i += num_pages;
> +       }
>  }
>  
>  void
> @@ -567,7 +578,7 @@ nouveau_bo_sync_for_cpu(struct nouveau_bo *nvbo)
>  {
>         struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
>         struct ttm_tt *ttm_dma = (struct ttm_tt *)nvbo->bo.ttm;
> -       int i;
> +       int i, j;
>  
>         if (!ttm_dma)
>                 return;
> @@ -576,9 +587,21 @@ nouveau_bo_sync_for_cpu(struct nouveau_bo *nvbo)
>         if (nvbo->force_coherent)
>                 return;
>  
> -       for (i = 0; i < ttm_dma->num_pages; i++)
> +       for (i = 0; i < ttm_dma->num_pages; ++i) {
> +               struct page *p = ttm_dma->pages[i];
> +               size_t num_pages = 1;
> +
> +               for (j = i + 1; j < ttm_dma->num_pages; ++j) {
> +                       if (++p != ttm_dma->pages[j])
> +                               break;
> +
> +                       ++num_pages;
> +               }
> +
>                 dma_sync_single_for_cpu(drm->dev->dev, ttm_dma-
> >dma_address[i],
> -                                       PAGE_SIZE, DMA_FROM_DEVICE);
> +                                       num_pages * PAGE_SIZE,
> DMA_FROM_DEVICE);
> +               i += num_pages;
> +       }
>  }
>  
>  void nouveau_bo_add_io_reserve_lru(struct ttm_buffer_object *bo)

-- 
Sincerely,
   Lyude Paul (she/her)
   Software Engineer at Red Hat
   
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