Hi Laurent,
On Mon, Jan 4, 2016 at 1:09 PM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> On Sun, Dec 27, 2015 at 9:20 AM, Laurent Pinchart
> <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
>> On Tuesday 22 December 2015 14:43:34 Geert Uytterhoeven wrote:
>>> On Thu, Dec 17, 2015 at 8:21 AM, Laurent Pinchart wrote:
>>> > diff --git a/arch/arm64/boot/dts/renesas/r8a7795.dtsi
>>> > b/arch/arm64/boot/dts/renesas/r8a7795.dtsi index
>>> > 9ce6a5ea6629..47f97ffc6c8b 100644
>>> > --- a/arch/arm64/boot/dts/renesas/r8a7795.dtsi
>>> > +++ b/arch/arm64/boot/dts/renesas/r8a7795.dtsi
>>> > @@ -775,5 +775,119 @@
>>> > clocks = <&cpg CPG_MOD 915>;
>>> > status = "disabled";
>>> > };
>>> > +
>>> > + vspbc: vsp@fe920000 {
>>> > + compatible = "renesas,vsp2";
>>> > + reg = <0 0xfe920000 0 0x8000>;
>>> > + interrupts = <GIC_SPI 266 IRQ_TYPE_LEVEL_HIGH>;
>>> > + clocks = <&cpg CPG_MOD 624>;
>>>
>>> No "power-domains = <&cpg_clocks>;"?
>>> Each vsp device node corresponds nicely to one vsp module, and the driver
>>> doesn't care at all about the clock, except for (explicit) PM of the vsp
>>> modules.
>>>
>>> That would allow to simplify vsp1_device_get(), vsp1_pm_suspend(), and
>>> vsp1_pm_resume(), and get rid of vsp1_device_put() in favor of
>>> pm_runtime_put().
>>
>> I'm all for simplification :-) I'll try to find time to move the driver to
>> runtime PM. What will happen if the power domain is specified in DT but the
>
> Thanks!
>
>> driver doesn't use runtime PM yet ?
>
> The device will be added to the PM Domain, but the PM Domain will not be
> turned on, and the gpd_dev_ops.start() callback will never be called for the
> device. You need to call pm_runtime_enable() and pm_runtime_get_sync() to
> do that.
>
> The CPG/MSSR PM Domain is a Clock Domain, so the driver can choose to manage
> the device's modulo clock itself instead of relying on the gpd_dev_ops.start()
> callback. But if a VSP IP core ever ends up in an SoC with a hardware Power
> Domain[*], the hardware Power Domain may not be managed correctly.
> Unlike for clocks, you cannot escape proper Runtime PM when dealing with
> hardware Power Domains ;-)
Upon closer look, the VSP instances are actually located in a hardware Power
Domain (AV3P) on r8a7795, so we need support for SYSC Power Domains soon...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
