[Linux 2.6.2] bttv0: skipped frame. no signal? high irq latency?

[Linux 2.6.2] bttv0: skipped frame. no signal? high irq latency?

[Rui Saraiva]

Hello Gerd Knorr,

I've the dmesg full of this warnings (last 149 messages right now),
although I didn't notice anything unusual in tvtime. I don't recall seeing
those warnings with 2.4.x. Should I just ignore them? Is there anything I
could try?

~> dmesg | sort | uniq
bttv0: skipped frame. no signal? high irq latency? [main=43e5000,o_vbi=43e5018,o_field=603b000,rc=603b01c]
bttv0: skipped frame. no signal? high irq latency? [main=43e5000,o_vbi=43e5018,o_field=8cd7000,rc=8cd701c]
bttv0: skipped frame. no signal? high irq latency? [main=43e5000,o_vbi=43e5018,o_field=967a000,rc=967a01c]
bttv0: skipped frame. no signal? high irq latency? [main=43e5000,o_vbi=43e5018,o_field=a05b000,rc=a05b01c]


* Messages when the modules are loaded:

Linux video capture interface: v1.00
bttv: driver version 0.9.12 loaded
bttv: using 4 buffers with 2080k (520 pages) each for capture
bttv: Bt8xx card found (0).
bttv0: Bt878 (rev 17) at 0000:00:0d.0, irq: 11, latency: 32, mmio: 0xe7000000
bttv0: detected: Hauppauge WinTV [card=10], PCI subsystem ID is 0070:13eb
bttv0: using: Hauppauge (bt878) [card=10,autodetected]
bttv0: Hauppauge/Voodoo msp34xx: reset line init [5]
bttv0: Hauppauge eeprom: model=44344, tuner=LG TPI8PSB11D (29), radio=no
bttv0: i2c: checking for MSP34xx @ 0x80... found
msp34xx: init: chip=MSP3415G-B8 +nicam +simple +radio
bttv0: i2c: checking for TDA9875 @ 0xb0... not found
bttv0: i2c: checking for TDA7432 @ 0x8a... not found
tvaudio: TV audio decoder + audio/video mux driver
tvaudio: known chips: tda9840,tda9873h,tda9874h/a,tda9850,tda9855,tea6300,tea6420,tda8425,pic16c54 (PV951),ta8874z
bttv0: registered device video0
bttv0: registered device vbi0
bttv0: PLL: 28636363 => 35468950 .. ok

As you can see, I'm using "options bttv gbuffers=4" on /etc/modprobe.conf


* Relevant "lspci -vv" output:

00:0d.0 Multimedia video controller: Brooktree Corporation Bt878 Video Capture (rev 11)
        Subsystem: Hauppauge computer works Inc. WinTV Series
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66Mhz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 32 (4000ns min, 10000ns max)
        Interrupt: pin A routed to IRQ 11
        Region 0: Memory at e7000000 (32-bit, prefetchable) [size=4K]
        Capabilities: [44] Vital Product Data
        Capabilities: [4c] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-

00:0d.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture (rev 11)
        Subsystem: Hauppauge computer works Inc. WinTV Series
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66Mhz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR-
        Latency: 32 (1000ns min, 63750ns max)
        Interrupt: pin A routed to IRQ 11
        Region 0: Memory at e6800000 (32-bit, prefetchable) [size=4K]
        Capabilities: [44] Vital Product Data
        Capabilities: [4c] Power Management version 2
                Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-


You could find my .config at http://joel.ist.utl.pt/~rmps/config-2.6.2 and
if you need more info, just ask.


Regards,
  Rui Saraiva

Re: [Linux 2.6.2] bttv0: skipped frame. no signal? high irq latency?

[Gerd Knorr]

Rui Saraiva <rmps@joel.ist.utl.pt> writes:

> Hello Gerd Knorr,
> 
> I've the dmesg full of this warnings (last 149 messages right now),
> although I didn't notice anything unusual in tvtime. I don't recall seeing
> those warnings with 2.4.x. Should I just ignore them?

It's more or less a leftover debug message.  As it says bttv drops a
frame on every message.  That may happen due to a bad signal (or when
you switch to another channel) or due to high irq latencies,
i.e. bttv's irq handler not being called fast enough.

Unless that happens very frequently without channel switches
triggering this don't worry.

The patch below makes bttv quiet.

  Gerd

--- video4linux/bttv-driver.c~	2004-01-09 11:25:10.000000000 +0100
+++ video4linux/bttv-driver.c	2004-02-06 11:48:54.818360213 +0100
@@ -3308,8 +3308,8 @@
 	unsigned long flags;
 	
 	if (bttv_verbose) {
-		printk(KERN_INFO "bttv%d: timeout: irq=%d/%d, risc=%08x, ",
-		       btv->c.nr, btv->irq_me, btv->irq_total,
+		printk(KERN_INFO "bttv%d: timeout: drop=%d irq=%d/%d, risc=%08x, ",
+		       btv->c.nr, btv->framedrop, btv->irq_me, btv->irq_total,
 		       btread(BT848_RISC_COUNT));
 		bttv_print_irqbits(btread(BT848_INT_STAT),0);
 		printk("\n");
@@ -3378,7 +3378,8 @@
 	bttv_irq_next_set(btv, &new);
 	rc = btread(BT848_RISC_COUNT);
 	if (rc < btv->main.dma || rc > btv->main.dma + 0x100) {
-		if (1 /* irq_debug */)
+		btv->framedrop++;
+		if (irq_debug)
 			printk("bttv%d: skipped frame. no signal? high irq latency? "
 			       "[main=%lx,o_vbi=%lx,o_field=%lx,rc=%lx]\n",
 			       btv->c.nr,
--- video4linux/bttvp.h~	2004-01-09 11:20:11.000000000 +0100
+++ video4linux/bttvp.h	2004-02-06 11:47:16.086017583 +0100
@@ -402,9 +402,10 @@
 	struct bttv_suspend_state state;
 
 	/* stats */
+	unsigned int errors;
+	unsigned int framedrop;
 	unsigned int irq_total;
 	unsigned int irq_me;
-	unsigned int errors;
 
 	unsigned int users;
 	struct bttv_fh init;