On 08/10/2015 11:32 AM, Mauro Carvalho Chehab wrote: > Em Mon, 10 Aug 2015 10:31:03 +0200 > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > >> Hi Jungsak, >> >> On 07/31/2015 10:44 AM, Junghak Sung wrote: >>> Hello everybody, >>> >>> This is the 2nd round for refactoring Videobuf2(a.k.a VB2). >>> The purpose of this patch series is to separate existing VB2 framework >>> into core part and V4L2 specific part. So that not only V4L2 but also other >>> frameworks can use them to manage buffer and utilize queue. >>> >>> Why do we try to make the VB2 framework to be common? >>> >>> As you may know, current DVB framework uses ringbuffer mechanism to demux >>> MPEG-2 TS data and pass it to userspace. However, this mechanism requires >>> extra memory copy because DVB framework provides only read() system call for >>> application - read() system call copies the kernel data to user-space buffer. >>> So if we can use VB2 framework which supports streaming I/O and buffer >>> sharing mechanism, then we could enhance existing DVB framework by removing >>> the extra memory copy - with VB2 framework, application can access the kernel >>> data directly through mmap system call. >>> >>> We have a plan for this work as follows: >>> 1. Separate existing VB2 framework into three parts - VB2 common, VB2-v4l2. >>> Of course, this change will not affect other v4l2-based >>> device drivers. This patch series corresponds to this step. >>> >>> 2. Add and implement new APIs for DVB streaming I/O. >>> We can remove unnecessary memory copy between kernel-space and user-space >>> by using these new APIs. However, we leaves legacy interfaces as-is >>> for backward compatibility. >>> >>> This patch series is the first step for it. >>> The previous version of this patch series can be found at [1]. >>> >>> [1] RFC PATCH v1 - http://www.spinics.net/lists/linux-media/msg90688.html >> >> This v2 looks much better, but, as per my comment to patch 1/5, it needs a bit >> more work before I can do a really good review. I think things will be much >> clearer once patch 3 shows the code moving from core.c/h to v4l2.c/h instead >> of the other way around. That shouldn't be too difficult. > > Hans, > > I suggested Junkhak to do that. On his previous patchset, he did what > you're suggestiong, e. g moving things from vb2-core into vb2-v4l2, and > that resulted on patches big enough to not be catched by vger. Actually, that wasn't the reason why the patches became so big. I just reorganized the patch series as I suggested above (pretty easy to do) and the size of patch 3 went down. > Also, IMHO, it is cleared this way, as we can see what parts of VB2 will > actually be shared, as there are lots of things that won't be shared: > overlay, userptr, multiplanar. That's why I prefer to see what moves *out* from the core. To be honest, it depends on what your preference is. Junghak, just leave the patch as-is. However, for v3 you should run checkpatch.pl over the diff since it complained about various things. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
