Hi Chuanbo Weng, I suspect that the problem might be caused by difference between size of DMABUF object and buffer size in V4L2. What is the content of v4l2_format returned by VIDIOC_G_FMT? What is the content of V4l2_buffer structure passed by VIDIOC_QBUF?
Regards, Tomasz Stanislawski On 12/31/2013 03:42 AM, Chuanbo Weng wrote: > Hi Laurent, > > > 2013/12/29 Laurent Pinchart <laurent.pinch...@ideasonboard.com>: >> Hi Chuanbo, >> >> On Friday 27 December 2013 09:55:40 Chuanbo Weng wrote: >>>> Hi all, >>>> >>>> (My environment is intel platform, HD4000 GPU, kernel 3.10.19, logitech >>>> 270 webcam) >>>> >>>> As title said, I discover this issue when I run the program shown by >>>> Laurent Pinchart: >>>> http://www.mail-archive.com/linux-media@vger.kernel.org/msg54806.html >>>> >>>> If the frame is (width, height) = (640, 480), DMABUF works well. >>>> If the frame is (width, height) = (160, 120), v4lfd receives no event. >>>> >>>> And I dig into drm kernel code, find that: i915_gem_create will create a >>>> GPU buffer object on intel platform. The size of GPU bo will be bigger >>>> than frame size, for the reason that i915_gem_create will roundup the bo >>>> size to multiple of PAGE_SIZE when the frame is (width, height) = (160, >>>> 120). For (width, height) = (640, 480), the frame size is already multiple >>>> of PAGE_SIZE, so GPU bo is exactly equal to frame size. >> >> That should in theory not be an issue). This might be a stupid question, but >> have you tried to capture 160x120 images directly (with yavta for instance) >> without using DMABUF ? > > Thanks for your reply! Please forgive me if it's a stupid question > because I'm new in camera > and v4l2 region. Yes, of course, I have tried to capture 160x120 > images using yavta and v4l-utils > without using DMABUF (using MMAP), it works well. So it proves the > camera support this width > and height.I strongly recommend you to tried 160x120 images using > DMABUF on your machine, > because I have tried 3 cameras (two logiteh, one microsoft) and all of > them don't work. >> >>>> I also dump the uvc driver infomation, there is some infomation i >>>> think maybe important: >>>> uvcvideo: Stream 1 error event 07 01 len 4 >>>> >>>> Looking forward to the discussion! >> >> -- >> Regards, >> >> Laurent Pinchart >> > > Thanks, > Chuanbo Weng > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
