On Fri, Jan 09, 2009 at 09:48:07PM -0500, Andy Walls wrote: > On Thu, 2009-01-08 at 00:50 -0200, Mauro Carvalho Chehab wrote: > > On Sun, 4 Jan 2009 22:57:42 +0100 > > Marcin Slusarz <marcin.slusarz@xxxxxxxxx> wrote: > > > > > Hi > > > There's a race between saa7134 device initialization and first interrupt > > > handler, which manifests as an oops [1]. > > > > > > saa7134_initdev -> request_irq -> saa7134_irq -> > > > saa7134_irq_video_signalchange -> saa7134_tvaudio_setmute -> mute_input_7133 > > > > > > In mute_input_7133 dev->input == NULL and accessing dev->input->amux will oops, > > > because dev->input would be initialized later: > > > > > > saa7134_initdev -> saa7134_hwinit2 -> saa7134_video_init2 -> video_mux -> > > > saa7134_tvaudio_setinput > > > > > > I'm not sure how it should be fixed correctly, but one of attached patches > > > should fix the symptom. > > > > > > Marcin > > > > Hi Marcin, > > > > Probably, it is some locking trouble on saa7134 driver that appeared on 2.6.27, > > with the lack of KBL on newer kernels. cx88 driver is suffering similar > > troubles starting with 2.6.27. > > > > I'll try to find some time to review, but it would be better if someone volunteer himself to take a look on cx88 and saa7134 locks. > > Mauro & Marcin, > > This isn't a locking issue. This is a device initialization issue. It > also looks like it's been reported quite often under 2.6.25 as well. > > > Marcin, > > What devices share the interrupt with the SAA7133? > > $ cat /proc/interrupts > > And could on of those those devices possibly generate an interrupt while > the saa7134 driver is being modporbe'd? I don't have this hardware so I can't tell. I've picked random oops from kerneloops.org and tried to fix it. > > Mauro & Marcin, > > This looks like to me what is going on: > > saa7134_hwinit1() does properly turn off IRQs for which it wants > reports: > > saa_writel(SAA7134_IRQ1, 0); > saa_writel(SAA7134_IRQ2, 0); > > but not clearing the state of SAA7134_IRQ_REPORT, maybe something like > this (I don't have a SAA7134 datasheet): > > saa_writel(SAA7134_IRQ_REPORT, 0xffffffff); > > So when saa7134_initdev() calls request_irq(..., saa7134_irq, > IRQF_SHARED | IRQF_DISABLED, ...), it gets an IRQ that is shared with > another device. > > Before saa7134_hwinit2() is called by saa7134_initdev() to set > "dev->input", some other device fires an interrupt and saa7134_irq() is > called that then operates on the unknown state of the SAA7134_IRQ_REPORT > register that was never cleared. Sounds good. But I think this register should be set to 0, because in saa7134_irq, we do: report = saa_readl(SAA7134_IRQ_REPORT); (...) if ((report & SAA7134_IRQ_REPORT_RDCAP) || (report & SAA7134_IRQ_REPORT_INTL)) saa7134_irq_video_signalchange(dev); But I'm not v4l expert, so... > Marcin has mapped out the oops from there. > > So the solution, I'm guessing, is likely to clear the SAA7134_IRQ_REPORT > register in saa7134_hwinit1(). > > If only I had a datasheet, hardware, spare time... ;) > > > Regards, > Andy > > > > > Cheers, > > Mauro. > > > > > > > [1] http://kerneloops.org/guilty.php?guilty=mute_input_7133&version=2.6.27-release&start=1802240&end=1835007&class=oops > > > > > > --- > > > diff --git a/drivers/media/video/saa7134/saa7134-video.c b/drivers/media/video/saa7134/saa7134-video.c > > > index 02bb674..fcb0b17 100644 > > > --- a/drivers/media/video/saa7134/saa7134-video.c > > > +++ b/drivers/media/video/saa7134/saa7134-video.c > > > @@ -2585,7 +2585,8 @@ void saa7134_irq_video_signalchange(struct saa7134_dev *dev) > > > /* no video signal -> mute audio */ > > > if (dev->ctl_automute) > > > dev->automute = 1; > > > - saa7134_tvaudio_setmute(dev); > > > + if (dev->input) > > > + saa7134_tvaudio_setmute(dev); > > > } else { > > > /* wake up tvaudio audio carrier scan thread */ > > > saa7134_tvaudio_do_scan(dev); > > > --- > > > > > > or > > > > > > --- > > > diff --git a/drivers/media/video/saa7134/saa7134-tvaudio.c b/drivers/media/video/saa7134/saa7134-tvaudio.c > > > index 76b1640..75ee085 100644 > > > --- a/drivers/media/video/saa7134/saa7134-tvaudio.c > > > +++ b/drivers/media/video/saa7134/saa7134-tvaudio.c > > > @@ -917,6 +917,8 @@ int saa7134_tvaudio_rx2mode(u32 rx) > > > > > > void saa7134_tvaudio_setmute(struct saa7134_dev *dev) > > > { > > > + if (!dev->input) > > > + return; > > > switch (dev->pci->device) { > > > case PCI_DEVICE_ID_PHILIPS_SAA7130: > > > case PCI_DEVICE_ID_PHILIPS_SAA7134: > > > --- > > > > > -- 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
