Hi Mark,
On Tue, Feb 04, 2014 at 12:21:10AM +0000, Mark Brown wrote:
> On Fri, Jan 31, 2014 at 11:47:04PM +0100, Maxime Ripard wrote:
> > On Fri, Jan 31, 2014 at 12:48:09PM +0000, Mark Brown wrote:
> > > On Fri, Jan 31, 2014 at 11:55:50AM +0100, Maxime Ripard wrote:
>
> > > > + pm_runtime_enable(&pdev->dev);
> > > > + if (!pm_runtime_enabled(&pdev->dev)) {
> > > > + ret = sun6i_spi_runtime_resume(&pdev->dev);
> > > > + if (ret) {
> > > > + dev_err(&pdev->dev, "Couldn't resume the device\n");
> > > > + return ret;
> > > > + }
> > > > + }
>
> > > No, as discussed don't do this - notice how other drivers aren't written
> > > this way either. Like I said leave the device powered on startup and
> > > then let it be idled by runtime PM.
>
> > Well, some SPI drivers are actually written like that (all the tegra
>
> It's not been done consistently, no - that should be fixed.
>
> > SPI drivers for example). It's not an excuse, but waking up the device
> > only to put it back in suspend right away seems kind of
>
> It isn't awesome, no. Ideally the runtime PM code would do this but
> then you couldn't ifdef the operations which as far as I can tell is the
> main thing people want from disabling it and it gets complicated for
> devices that genuinely do power up on startup so here we are.
We discussed it with Kevin on IRC, and he suggested that we move that
pm_runtime initialization to the SPI core, but I guess that would also
mean that all drivers shouldn't ifdef the operations, so that the core
can call the runtime_resume callback directly.
However, I don't really get why any driver should be doing so, since
you still need these functions to at least to the device
suspend/resume in the probe/remove, and you don't really want to
duplicate the code.
Right now, about half of the SPI drivers using auto_runtime_pm are
using a ifdef, the other half is not.
> > inefficient. Plus, the pm_runtime_idle callback you suggested are
> > actually calling runtime_idle, while we want to call runtime_suspend.
>
> Yeah, I didn't actually check if I was looking at the right call there.
I was actually wrong, it does so in its very last line.
Thanks,
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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