Hello, I received a report of a case where cx88 video capture was failing on start and the dmesg was reporting an invalid opcode on the video IRQ handler. I did a bisect, and it looks like it's a result of the videobuf2 conversion done back in late 2014. A few notes:
1. It only seems to occur if both video and VBI are being used. I cannot reproduce the issue when doing video only. 2. It seems like it's some sort of order-of-operations issue when interacting with the video/vbi device nodes, since it only happens with the stock VLC and not tvtime. It could also be that VLC uses libzvbi, which access the VBI device in mmap mode, whereas tvtime still uses read() for VBI access. 3. The problem is readily reproducible on a stock Ubuntu 14.04 system, as well as with 16.04, using the stock VLC that ships with the distro. I'm testing with the following command line: vlc v4l:///dev/video0 :v4l2-vbi-dev=/dev/vbi0 Sometimes it doesn't happen on the first hit and you have to run it a few times, but I've never seen it take more than 5 executions for the failure to occur. 4. The problem occurs even when I blacklist the cx88-alsa driver. This is worth noting since cx88-alsa has a different issue that results in dumping out the RISC engine state, and I wanted to both ensure the two issues weren't confused for each other, nor that the ALSA interaction could be impacting the order of operations for interacting with the driver. Any suggestions on the best way to debug this without having to learn the intimate details of the RISC engine on the cx88? From the state of the RISC engine it looks like there is some issue with queuing the opcodes/arguments (where in some cases arguments are interpreted as opcodes), but this is certainly not my area of expertise. Thanks, Devin [ 54.427224] cx88[0]: irq vid [0x10088] vbi_risc1* vbi_risc2* opc_err* [ 54.427232] cx88[0]/0: video risc op code error [ 54.427238] cx88[0]: video y / packed - dma channel status dump [ 54.427241] cx88[0]: cmds: initial risc: 0x87cdb000 [ 54.427244] cx88[0]: cmds: cdt base : 0x00180440 [ 54.427247] cx88[0]: cmds: cdt size : 0x0000000c [ 54.427249] cx88[0]: cmds: iq base : 0x00180400 [ 54.427251] cx88[0]: cmds: iq size : 0x00000010 [ 54.427253] cx88[0]: cmds: risc pc : 0x87cdb03c [ 54.427256] cx88[0]: cmds: iq wr ptr : 0x0000010e [ 54.427258] cx88[0]: cmds: iq rd ptr : 0x00000102 [ 54.427260] cx88[0]: cmds: cdt current : 0x00000458 [ 54.427263] cx88[0]: cmds: pci target : 0x00000000 [ 54.427265] cx88[0]: cmds: line / byte : 0x00000000 [ 54.427267] cx88[0]: risc0: 0x80008000 [ sync resync count=0 ] [ 54.427271] cx88[0]: risc1: 0x1c000280 [ write sol eol count=640 ] [ 54.427276] cx88[0]: risc2: 0x87dc0000 [ arg #1 ] [ 54.427279] cx88[0]: risc3: 0x1c000280 [ write sol eol count=640 ] [ 54.427283] cx88[0]: iq 0: 0x70000000 [ jump count=0 ] [ 54.427286] cx88[0]: iq 1: 0x80008000 [ arg #1 ] [ 54.427289] cx88[0]: iq 2: 0x1c000280 [ write sol eol count=640 ] [ 54.427293] cx88[0]: iq 3: 0x87dc0000 [ arg #1 ] [ 54.427295] cx88[0]: iq 4: 0x1c000280 [ write sol eol count=640 ] [ 54.427300] cx88[0]: iq 5: 0x87dc0500 [ arg #1 ] [ 54.427302] cx88[0]: iq 6: 0x1c000280 [ write sol eol count=640 ] [ 54.427306] cx88[0]: iq 7: 0x87dc0a00 [ arg #1 ] [ 54.427309] cx88[0]: iq 8: 0x1c000280 [ write sol eol count=640 ] [ 54.427313] cx88[0]: iq 9: 0x87dc0f00 [ arg #1 ] [ 54.427315] cx88[0]: iq a: 0x1c000280 [ write sol eol count=640 ] [ 54.427319] cx88[0]: iq b: 0x87dc1400 [ arg #1 ] [ 54.427321] cx88[0]: iq c: 0x1c000280 [ write sol eol count=640 ] [ 54.427326] cx88[0]: iq d: 0x87dc1900 [ arg #1 ] [ 54.427328] cx88[0]: iq e: 0xd2000001 [ writecr irq2 count=1 ] [ 54.427332] cx88[0]: iq f: 0x0031c040 [ arg #1 ] [ 54.427334] cx88[0]: iq 10: 0x00180c00 [ arg #2 ] [ 54.427337] cx88[0]: iq 11: 0x6f60580c [ arg #3 ] [ 54.427339] cx88[0]: fifo: 0x00180c00 -> 0x183400 [ 54.427340] cx88[0]: ctrl: 0x00180400 -> 0x180460 [ 54.427342] cx88[0]: ptr1_reg: 0x00180eb8 [ 54.427344] cx88[0]: ptr2_reg: 0x00180458 [ 54.427347] cx88[0]: cnt1_reg: 0x00000007 [ 54.427349] cx88[0]: cnt2_reg: 0x00000000 -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com
