At Wed, 20 Dec 2006 13:29:58 -0500, David Cullen wrote: > > Takashi Iwai wrote: > > At Tue, 19 Dec 2006 10:12:54 -0500, > > David Cullen wrote: > >> In alsa-driver-1.0.13/acore/memalloc.c there is this section of code > >> > >> /* > >> * Hacks > >> */ > >> > >> #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 0) > >> #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 5) > >> > >> I am using a patched 2.6.13 kernel. Should I change that last line > >> to be KERNEL_VERSION(2, 6, 13)? > > > > That part is a workaround only for the old 2.6 kernels which cause > > Oops when NULL is passed to device pointer. So, it should be > > irrelevant. > > > > OK. After more closely examining that code, I see that for my > kernel, this code is used > > #else > > /* for 2.2/2.4 kernels */ > #if defined(CONFIG_PCI) || defined(CONFIG_ISA) || defined(__i386__) > #define dma_alloc_coherent(dev,size,addr,flags) > pci_alloc_consistent((struct pci_dev *)(dev),size,addr) > #define dma_free_coherent(dev,size,ptr,addr) > pci_free_consistent((struct pci_dev *)(dev),size,ptr,addr) > #elif CONFIG_SBUS > #define dma_alloc_coherent(dev,size,addr,flags) > sbus_alloc_consistent((struct sbus_dev *)(dev),size,addr) > #define dma_free_coherent(dev,size,ptr,addr) > sbus_free_consistent((struct sbus_dev *)(dev),size,ptr,addr) > #else > #error "Need a bus for dma_alloc_coherent()" > #endif > > Which means pci_alloc_consistent is called instead of > __dma_alloc_coherent. pci_alloc_consistent() is used only on 2.2/2.4 kernels. All 2.6.x kernels are using dma_alloc_coherent(). > >> Also, could you give me some pointers regarding my previous e-mails > >> regarding this issue: > >> > >> Takashi Iwai wrote: > >> > At Mon, 27 Nov 2006 17:01:52 -0500, > >> > David Cullen wrote: > >> >> > >> >> I am trying to get ALSA version 1.0.13 working on an AMCC PowerPC > >> >> PPC405EP Taihu board with a Sound Blaster Live! 24-bit 7.1 PCI > >> >> card. I am using a patched 2.6.13 kernel that comes with the > >> >> board. I built the kernel with the sound core built in and I > >> >> used the cross-compiler tools to build the ALSA driver, library, > >> >> and utils. When I run "speaker-test", it crashes in the ALSA > >> >> library. The problem is that the call to mmap in > >> >> > >> >> alsa-lib-1.0.13/src/pcm/pcm_mmap.c line 367 > >> >> > >> >> which looks like > >> >> > >> >> ptr = mmap(NULL, size, PROT_READ|PROT_WRITE, > >> >> MAP_FILE|MAP_SHARED, i->u.mmap.fd, i->u.mmap.offset); > >> >> > >> >> returns a pointer that appears to be valid (0x3001E000) but > >> >> causes a kernel OOPS when accessed. > >> >> > >> >> Previous calls to mmap in pcm_hw.c on lines 822 and 854 both > >> >> succeed, and the pointers returned can be successfully accessed, > >> >> but they use the status and control offsets as parameters to > >> >> mmap. > >> >> > >> >> I haved traced the problem on the target into the ALSA library > >> >> using gdb and into the kernel using kgdb and everything looks > >> >> like it works properly. If I disable the semaphore acquisition > >> >> in do_mmap2, I can print the contents of the address in kgdb > >> >> using > >> >> > >> >> (gdb) print ((char *)vma->vm_start)[0] > >> >> > >> >> after the call to vm_link in do_mmap_pgoff. However, the board > >> >> locks up after the print command. > >> >> > >> >> Anyone have any experience with this type of problem on PowerPC > >> >> systems? > >> > > >> > Possibly a memory coherency problem. The memory allocated via > >> > dma_alloc_coherent() isn't simply mmappable. > >> > > >> > An essential fix would be to add dma_mmap_coherent() to all > >> > architectures and use it for ALSA mmap. I made some patches quite > >> > ago, but left it rotten for the time being... > >> > > >> > >> How do I "add dma_mmap_coherent() to all architectures and use it > >> for ALSA mmap"? > > > > Well, for that, we need to patch the kernel itself and add > > dma_mmap_coherent() call. The problem is that the memory returned > > from dma_alloc_coherent() isn't the address of the really allocated > > pages in your case. Since the ALSA mmap mode obtains the page via > > virt_to_page(), this doesn't work. Thus, a new function, > > dma_mmap_coherent() is required to calculate the real page address and > > do the rest of low-level mmap jobs. > > Where would dma_mmap_coherent be placed? Which specific file? It's somewhere in arch/*/* directory. > Would I replace all calls to mmap with dma_mmap_coherent? I can > probably figure out how to implement it if you can give me an > example for another architecture. I tried looking at old patches on > the web, but I had difficulty understanding them. I think they were > for the ARM architecture. Yes, ARM has already it. > > A simple solution would be simply disable mmap. > > In pci/ca0106/ca0106_main.c, remove SNDRV_PCM_INFO_MMAP and > > SNDRV_PCM_INFO_MMAP_VALID from snd_ca0106_playback_hw and > > snd_ca0106_capture_hw structs. > > > > Also, disable #if defined(CONFIG_PPC) around > > snd_pcm_mmap_status_*() in core/pcm_native.c. > > > > This will reduce the sound system functionality (e.g. no dmix is > > available), though. > > At this point, if we can get speaker-test to work, we will be happy. > So dmix is not necessary (I believe...). However, I do not know > the complete details of the end user's application, so dmix may be > needed eventually. If you can give me a few pointers on how to > implement dma_mmap_coherent and sew it into ALSA, that would really > help. When mmap is disabled in the driver, change the default alsa-lib configuration, too. Either edit alsa-lib/src/conf/cards/CA0106.conf or override the default PCM configuration in /etc/asound.conf, such as pcm.!default plughw > > BTW, any chance to try a newer version of kernel? > > I don't want to debug the issues of old kernels but rather fix the > > latest kernel... > > Unfortunately, we're stuck with the 2.6.13 kernel. We are working > with the AMCC Taihu evaluation board, and the kernel source that > comes with it has been heavily patched to work with that board. > Upgrading the patches to work with a newer kernel is outside the > scope of what we agreed to do. If you cannot help us as long as we > use the older kernel, I will pass along the information to my manager. OK, that's what I was afraid of... Takashi ------------------------------------------------------------------------- Take Surveys. Earn Cash. 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