Em Mon, 10 Aug 2015 12:11:39 +0200 Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > 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. Ah, ok. > > 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. Yeah. I actually prefer to see what will be shared, because the non-shared code won't have changes (except for minor kABI things), while the shared code will be more affected :) > Junghak, just leave the patch as-is. However, for v3 you should run > checkpatch.pl over the diff since it complained about various things. There are two things here: 1) on patches that just move things around, we should not run checkpatch, as otherwise it would be a nightmare for review. Ok, as we're doing a remanufacturing, it is a good idea to run checkpatch at the end and see what should be fixed (or do it before), but this is out of the scope of the manufacturing. I can do that myself when applying the series. 2) For all other patches that are adding/changing the code, then Junghak should run checkpatch and fix (most) stuff complained there. Regards, Mauro -- 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
