Thoughts about suspending DVB C PCI device transparently

Hi all.

Once in a time I wrote into Mantis driver Suspend / resume code. The idea was, that bridge driver (mantis_dvb.c) will handle the suspend / resume transparently to the application.

With a PCI device this was rather easy to achieve. With xine, there was just a glitch with video and audio after resume.

So after suspend, frontend was tuned into the original frequency, and the DMA transfer state was restored.

Suspend:
1. Turn off possible DMA transfer if active (feeds > 0)
2. Remember tuner power on state.
3. Do tuner and fronted power off.

Resume:
1. Restore frontend and tuner power.
2. (feeds > 0)? Set frequency for the tuner.
3. (feeds > 0)? Restore DMA transfer into previous state.

What do you think about this?
I need some feedback: is it worth coding? Other needed code is usual suspend / resume stuff.

Is it worth powering off the tuner, if it isn't
used?

For my current usage, powering off the unused tuner gives more power savings than implementing suspend/resume.

Marko Ristola

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// suspend to standby, ram or disk.
int mantis_dvb_suspend(struct mantis_pci *mantis, pm_message_t
prevState, pm_message_t mesg)

{
        if (mantis->feeds > 0)

mantis_dma_stop(mantis);

        if (mantis->has_power)
                mantis_fe_powerdown(mantis); // power off tuner.

        return 0;
}

void mantis_dvb_resume(struct mantis_pci *mantis, pm_message_t prevMesg)

{
       // power on frontend and tuner.
       mantis_frontend_tuner_init(mantis);

       if (mantis->feeds > 0 && mantis->fe->ops.tuner_ops.init)
                (mantis->fe->ops.init)(mantis->fe);

        if (mantis->feeds > 0) {
                (mantis->fe->ops.set_frontend)(mantis->fe, NULL);
mantis_dma_start(mantis);
        }
}

Hi,

found this old email when searching for suspend issues, seems like a good idea. Just wondering - how many eg dvb drivers are there with working suspend/hibernate (all buses, not just PCI)? Me thinks only a small fraction, the rest will crash unless blacklisted by pm-utils?

Would it be worth to code a generic approach working around drivers that need to be blacklisted? It seems that because of eg firmware loading this might be the only way to get dvb drivers behave?

Richard