Re: [PATCH v13 2/2] rcar-csi2: add Renesas R-Car MIPI CSI-2 receiver driver

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Sakari,

Thanks for your feedback.

On 2018-04-04 23:13:57 +0300, Sakari Ailus wrote:

[snip]

> > > +	pm_runtime_enable(&pdev->dev);
> > 
> > Is CONFIG_PM mandatory on Renesas SoCs? If not, you end up with the
> > device uninitialised at probe, and pm_runtime_get_sync will not
> > initialise it either if CONFIG_PM is not enabled. I guess you could
> > call your runtime_resume function unconditionally, and mark the device
> > as active in runtime_pm using pm_runtime_set_active.
> 
> There doesn't seem to be any runtime_resume function. Was there supposed
> to be one?

No there is not suppose to be one.

> 
> Assuming runtime PM would actually do something here, you might add
> pm_runtime_idle() to power the device off after probing.
> 
> I guess pm_runtime_set_active() should precede pm_runtime_enable().

The CSI-2 is in the always on power domain so the calls to 
pm_runtime_get_sync() and pm_runtime_put() are there in the s_stream() 
callback to enable and disable the module clock. I'm no expert on PM but 
in my testing the pm_ calls in this driver seems to be correct.

1. In probe I call pm_runtime_enable(). And rudimentary tests shows the 
   clock is off (but I might miss something) as I wish it to be until 
   stream on time.
2. In s_stream() I call pm_runtime_get_sync() before writing any 
   register when starting a stream. And likewise I call pm_runtime_put() 
   when stopping and I no longer need to write to a register.
3. In remove() I call pm_runtime_disable().

Am I missing something obvious here?

-- 
Regards,
Niklas Söderlund