> The central issue seems to be that I think media pad links / media bus > formats should describe physical links, such as parallel or serial > buses, and the formats of pixels flowing through them, whereas Steve > would like to extend them to describe software transports and in-memory > formats. This probably isn't the right place to attach this comment in this thread, but... the issue of media bus formats matching physical buses is an argument that I think is already lost. For example, take the 10-bit bayer formats: #define MEDIA_BUS_FMT_SBGGR10_1X10 0x3007 #define MEDIA_BUS_FMT_SGBRG10_1X10 0x300e #define MEDIA_BUS_FMT_SGRBG10_1X10 0x300a #define MEDIA_BUS_FMT_SRGGB10_1X10 0x300f These are commonly used on CSI serial buses (see the smiapp driver for example). From the description at the top of the file, it says the 1X10 means that one pixel is transferred as one 10-bit sample. However, the format on wire is somewhat different - four pixels are transmitted over five bytes: P0 P1 P2 P3 P0 P1 P2 P3 8-bit 8-bit 8-bit 8-bit 2-bit 2-bit 2-bit 2-bit This gives two problems: 1) it doesn't fit in any sensible kind of "one pixel transferred as N M-bit samples" description because the pixel/sample values (depending how you look at them) are broken up. 2) changing this will probably be a user visible change, as things like smiapp are already in use. So, I think what we actually have is the media bus formats describing the _logical_ bus format. Yes, one pixel is transferred as one 10-bit sample in this case. To help illustrate my point, consider the difference between MEDIA_BUS_FMT_RGB565_1X16 and MEDIA_BUS_FMT_RGB565_2X8_BE or MEDIA_BUS_FMT_RGB565_2X8_LE. RGB565_1X16 means 1 pixel over an effective 16-bit wide bus (if it's not 16-bit, then it has to be broken up into separate "samples".) RGB565_2X8 means 1 pixel as two 8-bit samples. So, the 10-bit bayer is 1 pixel as 1.25 bytes. Or is it, over a serial bus. Using the RGB565 case, 10-bit bayer over a 4 lane CSI bus becomes interesting: first byte 2nd 3rd lane 1 P0 9:2 S0 P7 9:2 lane 2 P1 9:2 P4 9:2 S1 lane 3 P2 9:2 P5 9:2 P8 9:2 lane 4 P3 9:2 P6 9:2 P9 9:2 S0 = P0/P1/P2/P3 least significant two bits S1 = P4/P5/P6/P7 least significant two bits or 2 lane CSI: first byte 2nd 3rd 4th 5th lane 1 P0 9:2 P2 S0 P5 P7 lane 2 P1 9:2 P3 P4 P6 S1 or 1 lane CSI: lane 1 P0 P1 P2 P3 S0 P4 P5 P6 P7 S1 P8 P9 ... etc. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
