Thought some people here might be interested in this too... Description
quoted below.
--
Jeff Garzik | "Mind if I drive?" -Sam
Building 1024 | "Not if you don't mind me clawing at the
MandrakeSoft | dash and screaming like a cheerleader."
| -Max
> This patch, against 2.4.0-test10-pre6, updates bttv to use the new and
> groovy method of supporting mmap.
>
> Advantages:
> * Code more simple.
> * mmap now only limited to number of free pages in the system (busts vmalloc limits)
> * mmap no longer requires vmalloc, or remap_page_range.
>
> Disadvantages:
> * Requires videodev API update (new member: mmap_vma).
> * KNOWN BUG: If your gbufsize causes a frame to cross a page boundary,
> you lose. The code doesn't support this, and doesn't check for it
> either. Boom. (this is fixable though)
> * Totally untested. I don't own any bttv hardware.
>
Index: include/linux/videodev.h =================================================================== RCS file: /cvsroot/gkernel/linux_2_4/include/linux/videodev.h,v retrieving revision 1.1.1.1 diff -u -r1.1.1.1 videodev.h --- include/linux/videodev.h 2000/10/22 19:36:11 1.1.1.1 +++ include/linux/videodev.h 2000/10/28 07:31:20 @@ -32,6 +32,7 @@ int busy; int minor; devfs_handle_t devfs_handle; + int (*mmap_vma)(struct file *, struct vm_area_struct *, struct video_device *); }; extern int videodev_init(void); Index: drivers/media/video/bttv-driver.c =================================================================== RCS file: /cvsroot/gkernel/linux_2_4/drivers/media/video/bttv-driver.c,v retrieving revision 1.1.1.2 diff -u -r1.1.1.2 bttv-driver.c --- drivers/media/video/bttv-driver.c 2000/10/22 22:02:34 1.1.1.2 +++ drivers/media/video/bttv-driver.c 2000/10/28 07:31:24 @@ -142,16 +142,6 @@ return ret; } -static inline unsigned long uvirt_to_bus(unsigned long adr) -{ - unsigned long kva, ret; - - kva = uvirt_to_kva(pgd_offset(current->mm, adr), adr); - ret = virt_to_bus((void *)kva); - MDEBUG(printk("uv2b(%lx-->%lx)", adr, ret)); - return ret; -} - static inline unsigned long kvirt_to_bus(unsigned long adr) { unsigned long va, kva, ret; @@ -163,79 +153,60 @@ return ret; } -/* Here we want the physical address of the memory. - * This is used when initializing the contents of the - * area and marking the pages as reserved. +/* + * Alloc and free DMA pages for mmap(2) */ -static inline unsigned long kvirt_to_pa(unsigned long adr) -{ - unsigned long va, kva, ret; - - va = VMALLOC_VMADDR(adr); - kva = uvirt_to_kva(pgd_offset_k(va), va); - ret = __pa(kva); - MDEBUG(printk("kv2pa(%lx-->%lx)", adr, ret)); - return ret; -} - -static void * rvmalloc(signed long size) + +static void free_dmabuffers(struct bttv *btv) { - void * mem; - unsigned long adr, page; + unsigned int i; - mem=vmalloc_32(size); - if (mem) - { - memset(mem, 0, size); /* Clear the ram out, no junk to the user */ - adr=(unsigned long) mem; - while (size > 0) - { - page = kvirt_to_pa(adr); - mem_map_reserve(virt_to_page(__va(page))); - adr+=PAGE_SIZE; - size-=PAGE_SIZE; - } + if (btv->page) { + for (i = 0; i < btv->n_pages; i++) + if (btv->page[i].cpuaddr) + pci_free_consistent (btv->dev, PAGE_SIZE, + btv->page[i].cpuaddr, + btv->page[i].handle); + memset(btv->page, 0, sizeof(btv->page) * btv->n_pages); + btv->n_pages = 0; + kfree(btv->page); + btv->page = NULL; } - return mem; } -static void rvfree(void * mem, signed long size) +static int alloc_dmabuffers(struct bttv *btv) { - unsigned long adr, page; - - if (mem) - { - adr=(unsigned long) mem; - while (size > 0) - { - page = kvirt_to_pa(adr); - mem_map_unreserve(virt_to_page(__va(page))); - adr+=PAGE_SIZE; - size-=PAGE_SIZE; - } - vfree(mem); - } -} + unsigned int i; + if (btv->page) { + printk(KERN_ERR "bttv%d: Double alloc of DMA pages!\n", btv->nr); + return 0; + } + btv->n_pages = (gbuffers * gbufsize) >> PAGE_SHIFT; + if ((gbuffers * gbufsize) % PAGE_SIZE) + btv->n_pages++; -/* - * Create the giant waste of buffer space we need for now - * until we get DMA to user space sorted out (probably 2.3.x) - * - * We only create this as and when someone uses mmap - */ - -static int fbuffer_alloc(struct bttv *btv) -{ - if(!btv->fbuffer) - btv->fbuffer=(unsigned char *) rvmalloc(gbuffers*gbufsize); - else - printk(KERN_ERR "bttv%d: Double alloc of fbuffer!\n", - btv->nr); - if(!btv->fbuffer) - return -ENOBUFS; + btv->page = kmalloc (sizeof(btv->page) * btv->n_pages, GFP_KERNEL); + if (!btv->page) { + btv->n_pages = 0; + return -ENOMEM; + } + memset (btv->page, 0, sizeof(btv->page) * btv->n_pages); + + for (i = 0; i < btv->n_pages; i++) { + btv->page[i].cpuaddr = pci_alloc_consistent ( + btv->dev, PAGE_SIZE, &btv->page[i].handle); + if (!btv->page[i].cpuaddr) + goto err_out; + memset(btv->page[i].cpuaddr, 0, PAGE_SIZE); + } + return 0; + +err_out: + free_dmabuffers(btv); + return -ENOMEM; } @@ -1265,13 +1236,13 @@ static int vgrab(struct bttv *btv, struct video_mmap *mp) { unsigned int *ro, *re; - unsigned int *vbuf; + unsigned int *vbuf, page, page_ofs; unsigned long flags; - if(btv->fbuffer==NULL) + if (btv->page == NULL) { - if(fbuffer_alloc(btv)) - return -ENOBUFS; + int rc = alloc_dmabuffers(btv); + if (rc) return rc; } if(mp->frame >= gbuffers || mp->frame < 0) @@ -1294,7 +1265,9 @@ * Ok load up the BT848 */ - vbuf=(unsigned int *)(btv->fbuffer+gbufsize*mp->frame); + page = (gbufsize * mp->frame) >> PAGE_SHIFT; + page_ofs = (gbufsize * mp->frame) % PAGE_SIZE; + vbuf = (unsigned int *) (btv->page[page].cpuaddr + page_ofs); ro=btv->gbuf[mp->frame].risc; re=ro+2048; make_vrisctab(btv, ro, re, vbuf, mp->width, mp->height, mp->format); @@ -1433,9 +1406,8 @@ if (btv->user) goto out_unlock; - btv->fbuffer=(unsigned char *) rvmalloc(gbuffers*gbufsize); - ret = -ENOMEM; - if (!btv->fbuffer) + ret = alloc_dmabuffers(btv); + if (ret) goto out_unlock; btv->gq_in = 0; @@ -1495,9 +1467,8 @@ * We have allowed it to drain. */ - if(btv->fbuffer) - rvfree((void *) btv->fbuffer, gbuffers*gbufsize); - btv->fbuffer=0; + if (btv->page) + free_dmabuffers(btv); up(&btv->lock); MOD_DEC_USE_COUNT; } @@ -2166,45 +2137,81 @@ return 0; } +static struct page * bttv_mm_nopage (struct vm_area_struct * vma, + unsigned long address, int write_access) +{ + struct bttv *btv = vma->vm_private_data; + struct page *dmapage; + unsigned long pgoff; + + if (address > vma->vm_end) return NOPAGE_SIGBUS; /* Disallow mremap */ + if (!btv) return NOPAGE_OOM; /* Nothing allocated */ + + pgoff = vma->vm_pgoff + ((address - vma->vm_start) >> PAGE_SHIFT); + if (pgoff > btv->n_pages) return NOPAGE_SIGBUS; + + dmapage = virt_to_page (btv->page[pgoff].cpuaddr); + get_page (dmapage); + return dmapage; +} + +#ifndef VM_RESERVE +static int bttv_mm_swapout (struct page *page, struct file *filp) +{ + return 0; +} +#endif /* VM_RESERVE */ + +struct vm_operations_struct bttv_mm_ops = { + nopage: bttv_mm_nopage, +#ifndef VM_RESERVE + swapout: bttv_mm_swapout, +#endif +}; + /* * This maps the vmalloced and reserved fbuffer to user space. - * - * FIXME: - * - PAGE_READONLY should suffice!? - * - remap_page_range is kind of inefficient for page by page remapping. - * But e.g. pte_alloc() does not work in modules ... :-( */ -static int do_bttv_mmap(struct bttv *btv, const char *adr, unsigned long size) +static int do_bttv_mmap (struct file *file, struct vm_area_struct *vma, + struct bttv *btv) { - unsigned long start=(unsigned long) adr; - unsigned long page,pos; + int rc = -EINVAL; + unsigned long max_size, size, start, offset; - if (size>gbuffers*gbufsize) - return -EINVAL; - if (!btv->fbuffer) { - if(fbuffer_alloc(btv)) - return -EINVAL; - } - pos=(unsigned long) btv->fbuffer; - while (size > 0) { - page = kvirt_to_pa(pos); - if (remap_page_range(start, page, PAGE_SIZE, PAGE_SHARED)) - return -EAGAIN; - start+=PAGE_SIZE; - pos+=PAGE_SIZE; - size-=PAGE_SIZE; - } - return 0; + max_size = (gbuffers * gbufsize); + + start = vma->vm_start; + offset = (vma->vm_pgoff << PAGE_SHIFT); + size = vma->vm_end - vma->vm_start; + + /* some basic size/offset sanity checks */ + if (size > max_size) + goto out; + if (offset > max_size - size) + goto out; + + vma->vm_ops = &bttv_mm_ops; + vma->vm_private_data = btv; + +#ifdef VM_RESERVE + vma->vm_flags |= VM_RESERVE; +#endif + + rc = 0; + +out: + return rc; } -static int bttv_mmap(struct video_device *dev, const char *adr, unsigned long size) +static int bttv_mmap_vma(struct file *file, struct vm_area_struct *vma, + struct video_device *dev) { struct bttv *btv=(struct bttv *)dev; int r; down(&btv->lock); - r=do_bttv_mmap(btv, adr, size); + r=do_bttv_mmap(file, vma, btv); up(&btv->lock); return r; } @@ -2212,20 +2219,18 @@ static struct video_device bttv_template= { - "UNSET", - VID_TYPE_TUNER|VID_TYPE_CAPTURE|VID_TYPE_OVERLAY|VID_TYPE_TELETEXT, - VID_HARDWARE_BT848, - bttv_open, - bttv_close, - bttv_read, - bttv_write, - NULL, - bttv_ioctl, - bttv_mmap, - bttv_init_done, - NULL, - 0, - -1 + name: "UNSET", + type: VID_TYPE_TUNER|VID_TYPE_CAPTURE| + VID_TYPE_OVERLAY|VID_TYPE_TELETEXT, + hardware: VID_HARDWARE_BT848, + open: bttv_open, + close: bttv_close, + read: bttv_read, + write: bttv_write, + ioctl: bttv_ioctl, + mmap_vma: bttv_mmap_vma, + initialize: bttv_init_done, + minor: -1, }; @@ -2753,7 +2758,8 @@ memset(btv->vbibuf, 0, VBIBUF_SIZE); /* We don't want to return random memory to the user */ - btv->fbuffer=NULL; + btv->page = NULL; + btv->n_pages = 0; bt848_muxsel(btv, 1); bt848_set_winsize(btv); Index: drivers/media/video/bttv.h =================================================================== RCS file: /cvsroot/gkernel/linux_2_4/drivers/media/video/bttv.h,v retrieving revision 1.1.1.2 diff -u -r1.1.1.2 bttv.h --- drivers/media/video/bttv.h 2000/10/22 22:02:34 1.1.1.2 +++ drivers/media/video/bttv.h 2000/10/28 07:31:24 @@ -251,6 +251,13 @@ unsigned long re; }; + +struct bttv_dma { + void *cpuaddr; + dma_addr_t handle; +}; + + struct bttv { struct video_device video_dev; struct video_device radio_dev; @@ -312,7 +319,9 @@ struct bttv_gbuf *gbuf; int gqueue[MAX_GBUFFERS]; int gq_in,gq_out,gq_grab,gq_start; - char *fbuffer; + + struct bttv_dma *page; + unsigned int n_pages; struct bttv_pll_info pll; unsigned int Fsc; Index: drivers/media/video/videodev.c =================================================================== RCS file: /cvsroot/gkernel/linux_2_4/drivers/media/video/videodev.c,v retrieving revision 1.1.1.1 diff -u -r1.1.1.1 videodev.c --- drivers/media/video/videodev.c 2000/10/22 21:28:40 1.1.1.1 +++ drivers/media/video/videodev.c 2000/10/28 07:31:24 @@ -227,7 +227,9 @@ { int ret = -EINVAL; struct video_device *vfl=video_device[MINOR(file->f_dentry->d_inode->i_rdev)]; - if(vfl->mmap) { + if (vfl->mmap_vma) + return vfl->mmap_vma (file, vma, vfl); + if (vfl->mmap) { lock_kernel(); ret = vfl->mmap(vfl, (char *)vma->vm_start, (unsigned long)(vma->vm_end-vma->vm_start));
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This archive was generated by hypermail 2b29 : Tue Oct 31 2000 - 21:00:23 EST