[PATCH V3 10/19] drm/tegra: dc: Prepare for generic PM domains

On Tue, Jul 28, 2015 at 09:30:04AM +0100, Jon Hunter wrote:

On 17/07/15 11:41, Thierry Reding wrote:

quoted

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On Mon, Jul 13, 2015 at 01:39:48PM +0100, Jon Hunter wrote:

quoted

Add support to the tegra dc driver for generic PM domains. However,
to ensure backward compatibility with older device tree blobs ensure
that the driver can work with or without generic PM domains. In order
to migrate to generic PM domain infrastructure the necessary changes
are:

1. If the "power-domains" property is present in the DT device node then
   generic PM domains is supported and pm_runtime_enable() should be
   called for the device. Furthermore, the enabling and disabling of the
   power-domain is handled via calling pm_runtime_get/put, respectively.

The device could be PM runtime enabled even if no power-domains property
is set. Couldn't we check something more direct, like for example if the
dev->pm_domain is non-NULL?

Yes could do that instead.

quoted

Perhaps it'd be worth converting the driver to use runtime PM first, and
move all the powergate and clock handling into suspend/resume functions,
and then we can conditionalize whether or not we call the legacy API iff
dev->pm_domain == NULL?

May be that would be a cleaner transition than trying to do it all in
one go.

I have a couple of patches in my tree to do this for DRM as part of an
effort to restore DPMS. It's fairly tricky to get right in DRM and
requires all sorts of changes to the driver.

Thierry
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