Hi Hans, Thanks for your point and videobuf2 is also what I want to use. But since our development kernel version right now is still 2.6.35, I need to find way to work with current videobuf framework. Thanks Wen >-----Original Message----- >From: Hans Verkuil [mailto:hverkuil@xxxxxxxxx] >Sent: 2011å2æ9æ 15:52 >To: Wang, Wen W; Jozef Kruger >Cc: Kanigeri, Hari K; Iyer, Sundar; Yang, Jianwei; linux-media@xxxxxxxxxxxxxxx >Subject: Re: Memory allocation in Video4Linux > >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: 2011å2æ9æ 15:22 >> >To: Iyer, Sundar; Wang, Wen W; Yang, Jianwei; linux-media@xxxxxxxxxxxxxxx; >> >umg-meego-handset-kernel@xxxxxxxxxxxxxxxxxxxxxxx >> >Cc: Jozef Kruger >> >Subject: RE: Memory allocation in Video4Linux >> > >> > >> > >> >> -----Original Message----- >> >> From: umg-meego-handset-kernel-bounces@xxxxxxxxxxxxxxxxxxxxxxx >> >> [mailto:umg-meego-handset-kernel-bounces@xxxxxxxxxxxxxxxxxxxxxxx] On >> >> Behalf Of Iyer, Sundar >> >> Sent: Wednesday, February 09, 2011 12:20 PM >> >> To: Wang, Wen W; Yang, Jianwei; linux-media@xxxxxxxxxxxxxxx; umg-meego- >> >> handset-kernel@xxxxxxxxxxxxxxxxxxxxxxx >> >> 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 >> ïçï.nïïïïï+%ïïéèïwïï.nïïäï{çgïïîïïnïrâïïïïïãî&ïï >åzçïïïïzfïïïïïïïïïïïïïèz_çï:+vïî)æï >> >> > >-- >Hans Verkuil - video4linux developer - sponsored by Cisco ÿô.nlj·Ÿ®‰†+%ŠË±é¥Šwÿº{.nlj·¥Š{±þg‰¯â^n‡r¡öë¨è&£ûz¹Þúzf£¢·hšˆ§~††Ûÿÿïÿ‘ê_èæ+v‰¨þ)ßø
