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Date: Thu, 25 Nov 2021 10:17:29 +0200
From: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
To: tomba@...nel.org, Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: matthijsvanduin@...il.com, airlied@...ux.ie, daniel@...ll.ch,
linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
merlijn@...zup.org, philipp@...s.xyz,
laurent.pinchart@...asonboard.com
Subject: Re: [PATCH v3] drm: omapdrm: Export correct scatterlist for TILER
backed BOs
Gentle ping.
On 19.11.21 г. 10:06 ч., Ivaylo Dimitrov wrote:
> Memory of BOs backed by TILER is not contiguous, but omap_gem_map_dma_buf()
> exports it like it is. This leads to (possibly) invalid memory accesses if
> another device imports such a BO.
>
> Fix that by providing sg that correctly describes TILER memory layout.
> Align TILER allocations to page, so importer to be able to correctly set
> its MMU if have one. Set export size accounting for the alignment. Also,
> make sure to destroy sg on unpin, as it is no longer valid.
>
> Tested on Motorola Droid4 by using GPU (sgx540) to render.
>
> Suggested-by: Matthijs van Duin <matthijsvanduin@...il.com>
> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
> ---
> drivers/gpu/drm/omapdrm/omap_gem.c | 79 ++++++++++++++++++++++++++++++-
> drivers/gpu/drm/omapdrm/omap_gem.h | 2 +
> drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 34 ++-----------
> 3 files changed, 85 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
> index 97e5fe6..54cb6ce 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c
> @@ -800,7 +800,7 @@ int omap_gem_pin(struct drm_gem_object *obj, dma_addr_t *dma_addr)
> if (omap_obj->flags & OMAP_BO_TILED_MASK) {
> block = tiler_reserve_2d(fmt,
> omap_obj->width,
> - omap_obj->height, 0);
> + omap_obj->height, PAGE_SIZE);
> } else {
> block = tiler_reserve_1d(obj->size);
> }
> @@ -862,6 +862,11 @@ static void omap_gem_unpin_locked(struct drm_gem_object *obj)
> return;
>
> if (refcount_dec_and_test(&omap_obj->dma_addr_cnt)) {
> + if (omap_obj->sgt) {
> + sg_free_table(omap_obj->sgt);
> + kfree(omap_obj->sgt);
> + omap_obj->sgt = NULL;
> + }
> ret = tiler_unpin(omap_obj->block);
> if (ret) {
> dev_err(obj->dev->dev,
> @@ -974,6 +979,78 @@ int omap_gem_put_pages(struct drm_gem_object *obj)
> return 0;
> }
>
> +struct sg_table *omap_gem_get_sg(struct drm_gem_object *obj)
> +{
> + struct omap_gem_object *omap_obj = to_omap_bo(obj);
> + dma_addr_t addr;
> + struct sg_table *sgt;
> + struct scatterlist *sg;
> + unsigned int count, len, stride, i;
> + int ret;
> +
> + ret = omap_gem_pin(obj, &addr);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + mutex_lock(&omap_obj->lock);
> +
> + sgt = omap_obj->sgt;
> + if (sgt)
> + goto out;
> +
> + sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
> + if (!sgt) {
> + ret = -ENOMEM;
> + goto err_unpin;
> + }
> +
> + if (omap_obj->flags & OMAP_BO_TILED_MASK) {
> + enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
> +
> + len = omap_obj->width << (int)fmt;
> + count = omap_obj->height;
> + stride = tiler_stride(fmt, 0);
> + } else {
> + len = obj->size;
> + count = 1;
> + stride = 0;
> + }
> +
> + ret = sg_alloc_table(sgt, count, GFP_KERNEL);
> + if (ret)
> + goto err_free;
> +
> + for_each_sg(sgt->sgl, sg, count, i) {
> + sg_set_page(sg, phys_to_page(addr), len, offset_in_page(addr));
> + sg_dma_address(sg) = addr;
> + sg_dma_len(sg) = len;
> +
> + addr += stride;
> + }
> +
> + omap_obj->sgt = sgt;
> +out:
> + mutex_unlock(&omap_obj->lock);
> + return sgt;
> +
> +err_free:
> + kfree(sgt);
> +err_unpin:
> + mutex_unlock(&omap_obj->lock);
> + omap_gem_unpin(obj);
> + return ERR_PTR(ret);
> +}
> +
> +void omap_gem_put_sg(struct drm_gem_object *obj, struct sg_table *sgt)
> +{
> + struct omap_gem_object *omap_obj = to_omap_bo(obj);
> +
> + if (WARN_ON(omap_obj->sgt != sgt))
> + return;
> +
> + omap_gem_unpin(obj);
> +}
> +
> #ifdef CONFIG_DRM_FBDEV_EMULATION
> /*
> * Get kernel virtual address for CPU access.. this more or less only
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.h b/drivers/gpu/drm/omapdrm/omap_gem.h
> index eda9b48..19209e3 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.h
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.h
> @@ -82,5 +82,7 @@ int omap_gem_get_pages(struct drm_gem_object *obj, struct page ***pages,
> int omap_gem_rotated_dma_addr(struct drm_gem_object *obj, u32 orient,
> int x, int y, dma_addr_t *dma_addr);
> int omap_gem_tiled_stride(struct drm_gem_object *obj, u32 orient);
> +struct sg_table *omap_gem_get_sg(struct drm_gem_object *obj);
> +void omap_gem_put_sg(struct drm_gem_object *obj, struct sg_table *sgt);
>
> #endif /* __OMAPDRM_GEM_H__ */
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> index f4cde3a..95a9a89 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> @@ -21,45 +21,21 @@ static struct sg_table *omap_gem_map_dma_buf(
> {
> struct drm_gem_object *obj = attachment->dmabuf->priv;
> struct sg_table *sg;
> - dma_addr_t dma_addr;
> - int ret;
> -
> - sg = kzalloc(sizeof(*sg), GFP_KERNEL);
> - if (!sg)
> - return ERR_PTR(-ENOMEM);
> -
> - /* camera, etc, need physically contiguous.. but we need a
> - * better way to know this..
> - */
> - ret = omap_gem_pin(obj, &dma_addr);
> - if (ret)
> - goto out;
> -
> - ret = sg_alloc_table(sg, 1, GFP_KERNEL);
> - if (ret)
> - goto out;
> -
> - sg_init_table(sg->sgl, 1);
> - sg_dma_len(sg->sgl) = obj->size;
> - sg_set_page(sg->sgl, pfn_to_page(PFN_DOWN(dma_addr)), obj->size, 0);
> - sg_dma_address(sg->sgl) = dma_addr;
> + sg = omap_gem_get_sg(obj);
> + if (IS_ERR(sg))
> + return sg;
>
> /* this must be after omap_gem_pin() to ensure we have pages attached */
> omap_gem_dma_sync_buffer(obj, dir);
>
> return sg;
> -out:
> - kfree(sg);
> - return ERR_PTR(ret);
> }
>
> static void omap_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
> struct sg_table *sg, enum dma_data_direction dir)
> {
> struct drm_gem_object *obj = attachment->dmabuf->priv;
> - omap_gem_unpin(obj);
> - sg_free_table(sg);
> - kfree(sg);
> + omap_gem_put_sg(obj, sg);
> }
>
> static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
> @@ -112,7 +88,7 @@ struct dma_buf *omap_gem_prime_export(struct drm_gem_object *obj, int flags)
> DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
>
> exp_info.ops = &omap_dmabuf_ops;
> - exp_info.size = obj->size;
> + exp_info.size = omap_gem_mmap_size(obj);
> exp_info.flags = flags;
> exp_info.priv = obj;
>
>
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