On Wednesday, February 09, 2011 08:27:27 Wang, Wen W wrote: > Hi Hari, > > You are right. What we need is virtual address. > > Currently we alloc pages (alloc_pages()) for any request. Store those pages > for an image buffer into a list. We also manage the virtual address for ISP > by ourself (the range from 0 to 4GB) and the page table for our MMU which is > independent to system MMU page table.
Assuming you are using video4linux for this driver, then you should take a look at the new videobuf2 framework that will appear in 2.6.39. It is already in the media tree (http://git.linuxtv.org/media_tree.git, see include/media/videobuf2-core.h). It is much better than the old videobuf framework, and in particular gives the driver much more control on how memory is allocated and used. Regards, Hans > > Thanks > Wen > > >-----Original Message----- > >From: Kanigeri, Hari K > >Sent: 2011年2月9日 15:22 > >To: Iyer, Sundar; Wang, Wen W; Yang, Jianwei; [email protected]; > >[email protected] > >Cc: Jozef Kruger > >Subject: RE: Memory allocation in Video4Linux > > > > > > > >> -----Original Message----- > >> From: [email protected] > >> [mailto:[email protected]] On > >> Behalf Of Iyer, Sundar > >> Sent: Wednesday, February 09, 2011 12:20 PM > >> To: Wang, Wen W; Yang, Jianwei; [email protected]; umg-meego- > >> [email protected] > >> Cc: Jozef Kruger > >> Subject: Re: [Umg-meego-handset-kernel] Memory allocation in > >> Video4Linux > >> > >> I remember some Continous Memory Allocator (CMA) being iterated down a > >> few versions on > >> some mailing lists? IIRC, it is also for large buffers and management > >> for video IPs. > > > >I believe CMA is for allocating physically contiguous memory and from what > >Wen > >mentioned he also needs virtual memory management, which the IOMMU will > >provide. Please check the open source discussion on CMA, the last I heard CMA > >proposal was shot down. > >Reference: http://www.spinics.net/lists/linux-media/msg26875.html > > > >Wen, how are you currently allocating physical memory ? > > > > > >Thank you, > >Best regards, > >Hari > �翳�.n�����+%��遍荻�w��.n��伐�{炳g����n�r■�����ㄨ&｛�夸z罐����zf＂������������赙z_璁�:+v�)撸� > > -- Hans Verkuil - video4linux developer - sponsored by Cisco -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
