[Lima] [PATCH v2 1/2] drm/shmem-helper: Use cached mappings by default
Thomas Zimmermann
tzimmermann at suse.de
Sat Nov 7 18:56:39 UTC 2020
affects gm12u320; cc'ing Hans
Am 06.11.20 um 16:26 schrieb Thomas Zimmermann:
> SHMEM-buffer backing storage is allocated from system memory; which is
> typically cachable. The default mode for SHMEM objects is writecombine
> though.
>
> Unify SHMEM semantics by defaulting to cached mappings. The exception
> is pages imported via dma-buf. DMA memory is usually not cached.
>
> DRM drivers that require write-combined mappings set the map_wc flag
> in struct drm_gem_shmem_object to true. This currently affects lima,
> panfrost and v3d.
>
> The drivers mgag200, udl, virtio and vkms continue to use default
> shmem mappings.
>
> The drivers cirrus and gm12u320 change caching flags. Both used
> writecombine and now switch over to shmem defaults. Both drivers use
> SHMEM objects as shadow buffers for internal video memory, so cached
> mappings will not affect them negatively.
>
> v2:
> * recreate patch on top of latest SHMEM helpers
> * update lima, panfrost, v3d to select writecombine (Daniel, Rob)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---
> drivers/gpu/drm/drm_gem_shmem_helper.c | 11 ++++++-----
> drivers/gpu/drm/lima/lima_gem.c | 2 +-
> drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +-
> drivers/gpu/drm/v3d/v3d_bo.c | 2 +-
> drivers/gpu/drm/virtio/virtgpu_object.c | 1 -
> include/drm/drm_gem_shmem_helper.h | 4 ++--
> 6 files changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 8233bda4692f..ddec0e190f29 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -54,10 +54,12 @@ __drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
> if (!obj->funcs)
> obj->funcs = &drm_gem_shmem_funcs;
>
> - if (private)
> + if (private) {
> drm_gem_private_object_init(dev, obj, size);
> - else
> + shmem->map_wc = false; /* dma-buf mappings use always writecombine */
> + } else {
> ret = drm_gem_object_init(dev, obj, size);
> + }
> if (ret)
> goto err_free;
>
> @@ -278,7 +280,7 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
> if (ret)
> goto err_zero_use;
>
> - if (!shmem->map_cached)
> + if (shmem->map_wc)
> prot = pgprot_writecombine(prot);
> shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
> VM_MAP, prot);
> @@ -487,7 +489,6 @@ drm_gem_shmem_create_object_cached(struct drm_device *dev, size_t size)
> shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
> if (!shmem)
> return NULL;
> - shmem->map_cached = true;
>
> return &shmem->base;
> }
> @@ -616,7 +617,7 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>
> vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
> vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> - if (!shmem->map_cached)
> + if (shmem->map_wc)
> vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
> vma->vm_ops = &drm_gem_shmem_vm_ops;
>
> diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
> index 11223fe348df..bbab1413eb0c 100644
> --- a/drivers/gpu/drm/lima/lima_gem.c
> +++ b/drivers/gpu/drm/lima/lima_gem.c
> @@ -225,7 +225,7 @@ struct drm_gem_object *lima_gem_create_object(struct drm_device *dev, size_t siz
>
> mutex_init(&bo->lock);
> INIT_LIST_HEAD(&bo->va);
> -
> + bo->base.map_wc = true;
> bo->base.base.funcs = &lima_gem_funcs;
>
> return &bo->base.base;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index fb9f7334ce18..f77b72d995f9 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -230,7 +230,7 @@ struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t
> INIT_LIST_HEAD(&obj->mappings.list);
> mutex_init(&obj->mappings.lock);
> obj->base.base.funcs = &panfrost_gem_funcs;
> - obj->base.map_cached = pfdev->coherent;
> + obj->base.map_wc = !pfdev->coherent;
>
> return &obj->base.base;
> }
> diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c
> index 8b52cb25877c..6a8731ab9d7d 100644
> --- a/drivers/gpu/drm/v3d/v3d_bo.c
> +++ b/drivers/gpu/drm/v3d/v3d_bo.c
> @@ -78,7 +78,7 @@ struct drm_gem_object *v3d_create_object(struct drm_device *dev, size_t size)
> obj = &bo->base.base;
>
> obj->funcs = &v3d_gem_funcs;
> -
> + bo->base.map_wc = true;
> INIT_LIST_HEAD(&bo->unref_head);
>
> return &bo->base.base;
> diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
> index 2d3aa7baffe4..47e3b69c3927 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_object.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_object.c
> @@ -144,7 +144,6 @@ struct drm_gem_object *virtio_gpu_create_object(struct drm_device *dev,
>
> dshmem = &shmem->base.base;
> dshmem->base.funcs = &virtio_gpu_shmem_funcs;
> - dshmem->map_cached = true;
> return &dshmem->base;
> }
>
> diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
> index 5381f0c8cf6f..268d0284ae02 100644
> --- a/include/drm/drm_gem_shmem_helper.h
> +++ b/include/drm/drm_gem_shmem_helper.h
> @@ -98,9 +98,9 @@ struct drm_gem_shmem_object {
> unsigned int vmap_use_count;
>
> /**
> - * @map_cached: map object cached (instead of using writecombine).
> + * @map_wc: map object write-combined (instead of using shmem defaults).
> */
> - bool map_cached;
> + bool map_wc;
> };
>
> #define to_drm_gem_shmem_obj(obj) \
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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