Em 26-09-2011 08:21, Marek Szyprowski escreveu: > Hello, > > On Monday, September 26, 2011 1:14 PM Mauro Carvalho Chehab wrote: > >>> Scott Jiang (1): >>> vb2: add vb2_get_unmapped_area in vb2 core >> >>> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h >>> index ea55c08..977410b 100644 >>> --- a/include/media/videobuf2-core.h >>> +++ b/include/media/videobuf2-core.h >>> @@ -309,6 +309,13 @@ int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type); >>> int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type); >>> >>> int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma); >>> +#ifndef CONFIG_MMU >>> +unsigned long vb2_get_unmapped_area(struct vb2_queue *q, >>> + unsigned long addr, >>> + unsigned long len, >>> + unsigned long pgoff, >>> + unsigned long flags); >>> +#endif >>> unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait); >>> size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, >>> loff_t *ppos, int nonblock); >> >> This sounds me like a hack, as it is passing the problem of working with a non-mmu >> capable hardware to the driver, inserting architecture-dependent bits on them. >> >> The proper way to do it is to provide a vb2 core support to handle the non-mmu case >> inside it. > > This is exactly what this patch does - it provides generic vb2 implementation for > fops->get_unmapped_area callback which any vb2 ready driver can use. This operation > is used only on NON-MMU systems. Please check drivers/media/video/v4l2-dev.c file and > the implementation of get_unmapped_area there. Similar code is used by uvc driver. At least there, there is a: #ifdef CONFIG_MMU #define v4l2_get_unmapped_area NULL #else ... #endif block, so, in thesis, a driver can be written to support both cases without inserting #ifdefs inside it. Ideally, I would prefer if all those iommu-specific calls would be inside the core. A driver should not need to do anything special in order to support a different (sub)architecture. > > Best regards -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
