Hi Wolfram,
> > -----Original Message-----
> > From: linux-usb-owner@xxxxxxxxxxxxxxx <linux-usb-
> owner@xxxxxxxxxxxxxxx>
> > On Behalf Of Wolfram Sang
> > Sent: Saturday, May 25, 2019 12:57 PM
> > To: Ajay Gupta <ajaykuee@xxxxxxxxx>
> > Cc: heikki.krogerus@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; linux-
> > i2c@xxxxxxxxxxxxxxx; Ajay Gupta <ajayg@xxxxxxxxxx>
> > Subject: Re: [PATCH v3 2/5] i2c: nvidia-gpu: add runtime pm support
> >
> >
> > > @@ -211,6 +212,8 @@ static int gpu_i2c_master_xfer(struct i2c_adapter
> > *adap,
> > > goto exit;
> > > }
> > >
> > > + pm_runtime_mark_last_busy(i2cd->dev);
> > > + pm_runtime_put_autosuspend(i2cd->dev);
> > > return i;
> > > exit:
> > > if (send_stop) {
> > > @@ -218,6 +221,8 @@ static int gpu_i2c_master_xfer(struct i2c_adapter
> > *adap,
> > > if (status2 < 0)
> > > dev_err(i2cd->dev, "i2c stop failed %d\n", status2);
> > > }
> > > + pm_runtime_mark_last_busy(i2cd->dev);
> > > + pm_runtime_put_autosuspend(i2cd->dev);
> >
> > Maybe another worthwhile refactorization possible here? The exit code
> path
> > and 'all good' code path look very similar.
> > This can be done incrementally, though. I think for now it is okay.
> Thanks for suggestion. Yes , it is possible to refactor a bit further here.
>
> > > +static __maybe_unused int gpu_i2c_suspend(struct device *dev) {
> > > + return 0;
> > > +}
> >
> > Why do we need this?
> I2C function of PCI bus remains in D0 (lspci output) without this function.
Do you still see any issue with gpu_i2c_suspend()?
Thanks
Ajay
> nvpublic
>
> Following document also seems to insist on this.
> " For this to work, the device's driver has to provide a
> pm->runtime_suspend() callback "
>
> Documentation/power/pci.txt
> "First, a PCI device is put into a low-power state, or suspended, with the help
> of pm_schedule_suspend() or pm_runtime_suspend() which for PCI devices
> call
> pci_pm_runtime_suspend() to do the actual job. For this to work, the
> device's
> driver has to provide a pm->runtime_suspend() callback (see below), which
> is
> run by pci_pm_runtime_suspend() as the first action. If the driver's callback
> returns successfully, the device's standard configuration registers are saved,
> the device is prepared to generate wakeup signals and, finally, it is put into
> the target low-power state."
>
> Thanks
> Ajay
> > nvpublic
