And can you explain where is problem with memcpy in kernel? is it really that big problem to copy 720*576*3 bytes from kernel space to user space ? what all usb camera drivers do ? some dma access directly to destination buffer? On Tue, Apr 9, 2013 at 12:11 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > On Tue 9 April 2013 11:57:51 Michal Lazo wrote: >> Amlogic provide only 2.6.34 driver >> can I expect big performance loss ? > > Why do so many companies stick to ancient kernels? I can never understand that. > > You have three options: > > 1) update their driver to a recent kernel > 2) create a v4l2 driver for 2.6.34. But in that case you can't use the videobuf2 > framework which appeared in a later kernel and which greatly simplifies the > work of writing a v4l2 driver. > 3) it's possible to backport the whole of drivers/media to a 2.6.34 kernel. It > will generate a huge patch (>30 MB), but you will have a modern V4L2 kernel > environment. > > Note that none of this matters for performance. I would pick either option 1 or 3. > > Instructions on how to do option 3 are: > > 1) Clone this git repo: http://git.linuxtv.org/hverkuil/cisco_build.git > 2) Switch to the cobalt-mainline branch. > 3) Edit patch-kernel.sh and modify the 'target', 'orig_source' and 'source' > paths. > 4) Run patch-kernel.sh > > The resulting media.patch file should apply cleanly to your source kernel. > Note that the source kernel should be your vendor supplied kernel without > any of your own patches that you might normally apply on top of it. > > Regards, > > Hans > >> >> On Tue, Apr 9, 2013 at 11:09 AM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >> > On Tue 9 April 2013 10:52:41 Michal Lazo wrote: >> >> As we have all source codes >> >> what do you advice ? >> > >> > Write your own driver. Good templates to look at are drivers/media/pci/sta2x11 >> > and drivers/media/platform/blackfin. >> > >> > The first is functionality-wise probably closer to what you need, but it's a pci >> > driver, so the blackfin platform driver can be used to look at the platform part. >> > >> > Pick as recent a kernel as you can, but 3.6 at minimum since it has the useful >> > vb2 helper functions that the sta2x11 driver also uses. >> > >> > Regards, >> > >> > Hans >> > >> >> >> >> >> >> On Tue, Apr 9, 2013 at 10:38 AM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >> >> > On Tue 9 April 2013 09:58:33 Michal Lazo wrote: >> >> >> I want to make API that will provide hw video decoder on Amlogic SOC >> >> >> it is ARM cortex 9 >> >> >> >> >> >> with some proprietary video decoder >> >> >> >> >> >> amlogic provide me with working example that generate output frames in >> >> >> amlvideo driver. >> >> >> It is v4l2 driver >> >> >> and it did memcpy to mmap userspace memory >> >> >> >> >> >> buffer_y_start=ioremap(cs0.addr,cs0.width*cs0.height); >> >> >> for(i=0;i<buf->vb.height;i++) { >> >> >> memcpy(vbuf + pos_dst, buffer_y_start+pos_src, buf->vb.width*3); >> >> >> pos_dst+=buf->vb.width*3; >> >> >> pos_src+= cs0.width; >> >> >> } >> >> >> >> >> >> I did it with one memcpy with same cpu load >> >> >> >> >> >> https://github.com/Pivosgroup/buildroot-linux-kernel/blob/master/drivers/media/video/amlvideo/amlvideo.c#L218 >> >> >> >> >> >> top get me 50% cpu load on this driver for 25fps PAL >> >> >> >> >> >> it is really too much >> >> >> >> >> >> and funny is that vivi driver(amlvideo is completely base on vivi) get >> >> >> me same cpu load >> >> > >> >> > Well, yes, because it is the memcpy that gives you all the load. >> >> > Of course, in a well-written driver the amlvideo buffers would be available >> >> > to userspace directly using mmap() and no memcpy would be needed. >> >> > >> >> > Basically amlogic gave you a crappy driver. >> >> > >> >> > Regards, >> >> > >> >> > Hans >> >> > >> >> >> >> >> >> it looks like memcpy isn't cached or something but I don't know how to >> >> >> identify problem >> >> >> Any idea how to identify this problem. >> >> >> >> >> >> On Mon, Apr 8, 2013 at 2:46 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >> >> >> > On Mon April 8 2013 14:42:32 Michal Lazo wrote: >> >> >> >> Hi >> >> >> >> 720x576 RGB 25, 30 fps and it take >> >> >> >> >> >> >> >> 25% cpu load on raspberry pi(ARM 700Mhz linux 3.6.11) or 8% on x86(AMD >> >> >> >> 2GHz linux 3.2.0-39) >> >> >> >> >> >> >> >> it is simply too much >> >> >> > >> >> >> > No, that's what I would expect. Note that vivi was substantially improved recently >> >> >> > when it comes to the image generation. That will be in the upcoming 3.9 kernel. >> >> >> > >> >> >> > This should reduce CPU load by quite a bit if memory serves. >> >> >> > >> >> >> > Regards, >> >> >> > >> >> >> > Hans >> >> >> > >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> On Mon, Apr 8, 2013 at 9:42 AM, Peter Senna Tschudin >> >> >> >> <peter.senna@xxxxxxxxx> wrote: >> >> >> >> > Dear Michal, >> >> >> >> > >> >> >> >> > The CPU intensive part of the vivi driver is the image generation. >> >> >> >> > This is not an issue for real drivers. >> >> >> >> > >> >> >> >> > Regards, >> >> >> >> > >> >> >> >> > Peter >> >> >> >> > >> >> >> >> > On Sun, Apr 7, 2013 at 9:32 PM, Michal Lazo <michal.lazo@xxxxxxxxxxx> wrote: >> >> >> >> >> Hi >> >> >> >> >> V4L2 driver vivi >> >> >> >> >> generate 25% cpu load on raspberry pi(linux 3.6.11) or 8% on x86(linux 3.2.0-39) >> >> >> >> >> >> >> >> >> >> player >> >> >> >> >> GST_DEBUG="*:3,v4l2src:3,v4l2:3" gst-launch-0.10 v4l2src >> >> >> >> >> device="/dev/video0" norm=255 ! video/x-raw-rgb, width=720, >> >> >> >> >> height=576, framerate=30000/1001 ! fakesink sync=false >> >> >> >> >> >> >> >> >> >> Anybody can answer me why? >> >> >> >> >> And how can I do it better ? >> >> >> >> >> >> >> >> >> >> I use vivi as base example for my driver >> >> >> >> >> -- >> >> >> >> >> 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 >> >> >> >> > >> >> >> >> > >> >> >> >> > >> >> >> >> > -- >> >> >> >> > Peter >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> -- Best Regards Michal Lazo Senior developer manager mdragon.org Slovakia -- 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
