On 03/11/2016 04:40 PM, Robert Jarzmik wrote: > Hans Verkuil <hverkuil@xxxxxxxxx> writes: > >> On 03/11/2016 02:41 PM, Robert Jarzmik wrote: >>> Hans Verkuil <hverkuil@xxxxxxxxx> writes: >> One area where I would like to see some helper functions is with respect to >> format/media bus processing. I played with this a little bit but it is surprisingly >> hard to do. A lot of devices have all sorts of weird and wonderful exceptions >> that make this quite problematic. > > I'm also worried about the initial probing, where the subdevice, be that an I2C > sensor or something else has to be available, ie. the v4l2_async_notifier and > its implications. > >>> Ah, that's a special case we need to discuss. >>> I've written in the commit message a chapter about a "special port of this >>> code". This is it. >>> >>> This usecase is when a user does the following : >>> - set format to 1280x1024, RGB565 >>> - REQBUF for MMAP buffers >>> - QBUF, capture, DQBUF >>> >>> - then set format to 640x480, RGB565 >>> => here the new format fits in the previously allocated video buffer >>> - QBUF >>> => the test in pxa_vb2_prepare() detects this, and calls pxa_buffer_init() >>> again >>> >>> Now if this usecase is impossible, then I'll do as you say to simplify the code >>> : use icd->sizeimage, remove the code in pxa_vb2_prepare(), etc ... >> >> Does this actually work with soc-camera? As far as I can see soc-camera returns >> -EBUSY in soc_camera_s_fmt_vid_cap() if you attempt to change the format while >> streaming. > > It's not "while streaming" in the described usecase, it's after streaming is > finished actually. I should have added in the third dash VIDIOC_STREAMON before > "capture" and VIDIOC_STREAMOFF after DQBUF. I think it's working, even if I had > not tried recently. I certainly don't care that much about the usecase, and I > won't feel sad dropping it :) Ah, OK. This use-case will probably work with soc-camera. What I would prefer is to remove the feature for this vb2 conversion and the following soc-camera removal. If you decide that the feature is desirable, then add it back in a final patch. The reason for this is that it is much easier for me to review this once the driver is no longer dependent on soc-camera. I don't have to jump from the pxa driver to the soc-camera framework and back just to trace if there are no corner cases that were forgotten. This feature is unusual (very few drivers support it) and so I would like to take a close look at it, ensuring everything is done correctly. 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
