Le lundi 11 septembre 2023 à 12:13 +0200, Christian König a écrit : > Am 11.09.23 um 04:30 schrieb Yong Wu: > > From: John Stultz <jstu...@google.com> > > > > This allows drivers who don't want to create their own > > DMA-BUF exporter to be able to allocate DMA-BUFs directly > > from existing DMA-BUF Heaps. > > > > There is some concern that the premise of DMA-BUF heaps is > > that userland knows better about what type of heap memory > > is needed for a pipeline, so it would likely be best for > > drivers to import and fill DMA-BUFs allocated by userland > > instead of allocating one themselves, but this is still > > up for debate. > > The main design goal of having DMA-heaps in the first place is to avoid > per driver allocation and this is not necessary because userland know > better what type of memory it wants.
If the memory is user visible, yes. When I look at the MTK VCODEC changes, this seems to be used for internal codec state and SHM buffers used to communicate with firmware. > > The background is rather that we generally want to decouple allocation > from having a device driver connection so that we have better chance > that multiple devices can work with the same memory. > > I once create a prototype which gives userspace a hint which DMA-heap to > user for which device: > https://patchwork.kernel.org/project/linux-media/patch/20230123123756.401692-2-christian.koe...@amd.com/ > > Problem is that I don't really have time to look into it and maintain > that stuff, but I think from the high level design that is rather the > general direction we should push at. > > Regards, > Christian. > > > > > Signed-off-by: John Stultz <jstu...@google.com> > > Signed-off-by: T.J. Mercier <tjmerc...@google.com> > > Signed-off-by: Yong Wu <yong...@mediatek.com> > > [Yong: Fix the checkpatch alignment warning] > > --- > > drivers/dma-buf/dma-heap.c | 60 ++++++++++++++++++++++++++++---------- > > include/linux/dma-heap.h | 25 ++++++++++++++++ > > 2 files changed, 69 insertions(+), 16 deletions(-) > > > > diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c > > index dcc0e38c61fa..908bb30dc864 100644 > > --- a/drivers/dma-buf/dma-heap.c > > +++ b/drivers/dma-buf/dma-heap.c > > @@ -53,12 +53,15 @@ static dev_t dma_heap_devt; > > static struct class *dma_heap_class; > > static DEFINE_XARRAY_ALLOC(dma_heap_minors); > > > > -static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, > > - unsigned int fd_flags, > > - unsigned int heap_flags) > > +struct dma_buf *dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, > > + unsigned int fd_flags, > > + unsigned int heap_flags) > > { > > - struct dma_buf *dmabuf; > > - int fd; > > + if (fd_flags & ~DMA_HEAP_VALID_FD_FLAGS) > > + return ERR_PTR(-EINVAL); > > + > > + if (heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS) > > + return ERR_PTR(-EINVAL); > > > > /* > > * Allocations from all heaps have to begin > > @@ -66,9 +69,20 @@ static int dma_heap_buffer_alloc(struct dma_heap *heap, > > size_t len, > > */ > > len = PAGE_ALIGN(len); > > if (!len) > > - return -EINVAL; > > + return ERR_PTR(-EINVAL); > > > > - dmabuf = heap->ops->allocate(heap, len, fd_flags, heap_flags); > > + return heap->ops->allocate(heap, len, fd_flags, heap_flags); > > +} > > +EXPORT_SYMBOL_GPL(dma_heap_buffer_alloc); > > + > > +static int dma_heap_bufferfd_alloc(struct dma_heap *heap, size_t len, > > + unsigned int fd_flags, > > + unsigned int heap_flags) > > +{ > > + struct dma_buf *dmabuf; > > + int fd; > > + > > + dmabuf = dma_heap_buffer_alloc(heap, len, fd_flags, heap_flags); > > if (IS_ERR(dmabuf)) > > return PTR_ERR(dmabuf); > > > > @@ -106,15 +120,9 @@ static long dma_heap_ioctl_allocate(struct file *file, > > void *data) > > if (heap_allocation->fd) > > return -EINVAL; > > > > - if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS) > > - return -EINVAL; > > - > > - if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS) > > - return -EINVAL; > > - > > - fd = dma_heap_buffer_alloc(heap, heap_allocation->len, > > - heap_allocation->fd_flags, > > - heap_allocation->heap_flags); > > + fd = dma_heap_bufferfd_alloc(heap, heap_allocation->len, > > + heap_allocation->fd_flags, > > + heap_allocation->heap_flags); > > if (fd < 0) > > return fd; > > > > @@ -205,6 +213,7 @@ const char *dma_heap_get_name(struct dma_heap *heap) > > { > > return heap->name; > > } > > +EXPORT_SYMBOL_GPL(dma_heap_get_name); > > > > struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) > > { > > @@ -290,6 +299,24 @@ struct dma_heap *dma_heap_add(const struct > > dma_heap_export_info *exp_info) > > kfree(heap); > > return err_ret; > > } > > +EXPORT_SYMBOL_GPL(dma_heap_add); > > + > > +struct dma_heap *dma_heap_find(const char *name) > > +{ > > + struct dma_heap *h; > > + > > + mutex_lock(&heap_list_lock); > > + list_for_each_entry(h, &heap_list, list) { > > + if (!strcmp(h->name, name)) { > > + kref_get(&h->refcount); > > + mutex_unlock(&heap_list_lock); > > + return h; > > + } > > + } > > + mutex_unlock(&heap_list_lock); > > + return NULL; > > +} > > +EXPORT_SYMBOL_GPL(dma_heap_find); > > > > static void dma_heap_release(struct kref *ref) > > { > > @@ -315,6 +342,7 @@ void dma_heap_put(struct dma_heap *h) > > kref_put(&h->refcount, dma_heap_release); > > mutex_unlock(&heap_list_lock); > > } > > +EXPORT_SYMBOL_GPL(dma_heap_put); > > > > static char *dma_heap_devnode(const struct device *dev, umode_t *mode) > > { > > diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h > > index f3c678892c5c..59e70f6c7a60 100644 > > --- a/include/linux/dma-heap.h > > +++ b/include/linux/dma-heap.h > > @@ -64,10 +64,35 @@ const char *dma_heap_get_name(struct dma_heap *heap); > > */ > > struct dma_heap *dma_heap_add(const struct dma_heap_export_info > > *exp_info); > > > > +/** > > + * dma_heap_find - get the heap registered with the specified name > > + * @name: Name of the DMA-Heap to find > > + * > > + * Returns: > > + * The DMA-Heap with the provided name. > > + * > > + * NOTE: DMA-Heaps returned from this function MUST be released using > > + * dma_heap_put() when the user is done to enable the heap to be unloaded. > > + */ > > +struct dma_heap *dma_heap_find(const char *name); > > + > > /** > > * dma_heap_put - drops a reference to a dmabuf heap, potentially freeing > > it > > * @heap: the heap whose reference count to decrement > > */ > > void dma_heap_put(struct dma_heap *heap); > > > > +/** > > + * dma_heap_buffer_alloc - Allocate dma-buf from a dma_heap > > + * @heap: DMA-Heap to allocate from > > + * @len: size to allocate in bytes > > + * @fd_flags: flags to set on returned dma-buf fd > > + * @heap_flags: flags to pass to the dma heap > > + * > > + * This is for internal dma-buf allocations only. Free returned buffers > > with dma_buf_put(). > > + */ > > +struct dma_buf *dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, > > + unsigned int fd_flags, > > + unsigned int heap_flags); > > + > > #endif /* _DMA_HEAPS_H */ >
