Hi Guennadi, On Fri, Apr 1, 2011 at 01:12, Guennadi Liakhovetski <g.liakhovetski@xxxxxx> wrote: > Hi all > > As discussed at the last V4L2 meeting in Warsaw, one of the prerequisites > to support fast switching between different image formats is an ability to > preallocate buffers of different sizes and handle them over to the driver > in advance. This avoids the need to allocate buffers at the time of > switching. This patch series is a first implementation of these ioctl()s, > implemented for the sh_mobile_ceu_camera soc-camera host driver. Tested on > an sh7722 migor SuperH platform. Yes, I know, documentation is missing > yet;-) > I will have to wait for documentation before doing a full review, it's hard to comment without it. Also, please mention how the new ioctls influence the state machine. Some questions and doubts I'm having: - Can you call CREATE more than once, before/after REQBUFS, for all streaming states? What about reading/writing? - Can driver decline CREATE if it is not supported? What if the format is not supported? - If we fail allocating in CREATE, should the whole queue be freed (as it is done in your patch I believe)? - I'm assuming REQBUFS(0) is to free buffers allocated with CREATE too? - Are we allowing DESTROY to free arbitrary span of buffers (i.e. those created with REQBUFS as well)? - Are "holes" in buffer indexes allowed? I don't like the ability to free an arbitrary span of buffers in the queue, it complicates checks in many places and I don't think is worth it... - I understand SUBMIT is optional? - Could you give an example of how this could be used in an application? -- Best regards, Pawel Osciak -- 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
