e9hack wrote: > Oliver Endriss wrote: > > After digging through the code, kernel DMA docs and the saa7146 > > datasheet, I think that we should remove the scatter-gatter voodoo > > from the budget and av7110 driver. ;-) > > > > What about the attached patch? > > - easy to understand and maintain > > - saves 1 page of memory (page table of the SAA7146 MMU) > > - saves PCI bandwidth (SAA7146 does not read page table anymore) > > > > Comments? > > > > pci_alloc_consistent() allocates uncached memory. This makes the > demuxer very slow. The 'scatter-gatter voodoo' is a better solution. Oops, you are right. Anyway, the current implementation is incomplete. If cached memory is used, there must be a call to pci_dma_sync_sg(...PCI_DMA_FROM_DEVICE) before data can be read. > If exist a function, which can allocate cached continuous physical memory, > you should replace pci_alloc_consistent() with this function. Afaics a combination of kmalloc() and pci_map_single() should do the trick. Of course, a call to pci_dma_sync_single(...PCI_DMA_FROM_DEVICE) must be added, too. Could a DMA expert please confirm this? CU Oliver -- -------------------------------------------------------- VDR Remote Plugin 0.3.9 available at http://www.escape-edv.de/endriss/vdr/ -------------------------------------------------------- _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
