Hi Michael, On Tuesday 03 July 2012 11:46:33 Michael Jones wrote: > Hi Laurent & co., > > I'm looking at the memory limitations in the omap3isp driver. 'struct > isp_video' contains member 'capture_mem', which is set separately for each > of our v4l2 video device nodes. The CCDC, for example, has capture_mem = > 4096 * 4096 * 3 = 48MB, while the previewer and resizer each have twice > that. Where do these numbers come from?
That's mostly historical. When developing the driver for the N900 we set a limit to avoid putting too much pressure on the system memory, and 3x8MP buffers was considered to be enough. We could raise the limit, remove it completely, or implement a policy mechanism to let a privileged userspace application specify limits. The later might be interesting as a core V4L2 mechanism. > Is the CCDC incapable of DMA'ing more than 48MB into memory? I know that > ISP_VIDEO_MAX_BUFFERS also limits the # of buffers, but I assume this is > basically an arbitrary number so we can have a finite array of > isp_video_buffer's. The 48MB, on the other hand, looks like it might have a > good reason. -- Regards, Laurent Pinchart -- 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
