linux-kernel - Re: [PATCH 2/4] arm64: dts: rockchip: Add RGA support to the PX30

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Date:   Thu, 16 Apr 2020 16:12:05 +0200
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     Johan Jonker <jbx6244@...il.com>
Cc:     linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jacob Chen <jacob-chen@...wrt.com>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Heiko Stuebner <heiko@...ech.de>,
        Hans Verkuil <hansverk@...co.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 2/4] arm64: dts: rockchip: Add RGA support to the PX30

On Thu 16 Apr 20, 16:02, Johan Jonker wrote:
> On 4/16/20 3:55 PM, Paul Kocialkowski wrote:
> > Hi,
> > 
> > On Thu 16 Apr 20, 15:44, Johan Jonker wrote:
> >> On 4/16/20 3:24 PM, Paul Kocialkowski wrote:
> >>> Hi,
> >>>
> >>> On Thu 16 Apr 20, 15:02, Johan Jonker wrote:
> >>>> Hi Paul,
> >>>>
> >>>> The conversion of rockchip-rga.txt to rockchip-rga.yaml by myself just
> >>>> has been approved by robh.
> >>>
> >>> Huh, I looked around for ongoing related work but missed it.
> >>> I'll definitely rebase on top of your series and use the yaml description
> >>> instead. Thanks!
> >>>
> >>>> Maybe place dts patches at the end of a patch serie.
> >>>> Could you include a &rga patch if your device is supported in mainline,
> >>>> so we can test with:
> >>>> make ARCH=arm64 dtbs_check
> >>>> DT_SCHEMA_FILES=Documentation/devicetree/bindings/media/rockchip-rga.yaml
> >>>
> >>> I tested with the PX30 EVB so I can surely add a node there if that turns
> >>> out necessary (see below).
> >>>
> >>>> Johan
> >>>>
> >>>> On 4/16/20 1:50 PM, Paul Kocialkowski wrote:
> >>>>> The PX30 features a RGA block: add the necessary node to support it.
> >>>>>
> >>>>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> >>>>> ---
> >>>>>  arch/arm64/boot/dts/rockchip/px30.dtsi | 11 +++++++++++
> >>>>>  1 file changed, 11 insertions(+)
> >>>>>
> >>>>> diff --git a/arch/arm64/boot/dts/rockchip/px30.dtsi b/arch/arm64/boot/dts/rockchip/px30.dtsi
> >>>>> index 75908c587511..4bfbee9d4123 100644
> >>>>> --- a/arch/arm64/boot/dts/rockchip/px30.dtsi
> >>>>> +++ b/arch/arm64/boot/dts/rockchip/px30.dtsi
> >>>>> @@ -1104,6 +1104,17 @@ vopl_mmu: iommu@...70f00 {
> >>>>>  		status = "disabled";
> >>>>>  	};
> >>>>>  
> >>>>> +	rga: rga@...80000 {
> >>>>> +		compatible = "rockchip,px30-rga";
> >>>>> +		reg = <0x0 0xff480000 0x0 0x10000>;
> >>>>> +		interrupts = <GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH 0>;
> >>>>> +		clocks = <&cru ACLK_RGA>, <&cru HCLK_RGA>, <&cru SCLK_RGA_CORE>;
> >>>>> +		clock-names = "aclk", "hclk", "sclk";
> >>>>> +		resets = <&cru SRST_RGA>, <&cru SRST_RGA_A>, <&cru SRST_RGA_H>;
> >>>>> +		reset-names = "core", "axi", "ahb";
> >>>>> +		power-domains = <&power PX30_PD_VO>;
> >>>>
> >>>> 		status = "disabled";
> >>>
> >>> As of 5.6, the rk3399 has the node enabled by default. Did that change?
> >>
> >> 'status' disappeared during review for rk3399 between v2 and v3, but
> >> doesn't mention the reason. If someone can give more info here?
> >>
> >> https://lore.kernel.org/lkml/1500101920-24039-5-git-send-email-jacob-chen@iotwrt.com/
> >>
> >> https://lore.kernel.org/lkml/1501470460-12014-5-git-send-email-jacob-chen@iotwrt.com/
> >>
> >>>
> >>> Since it's a standalone block that has no I/O dependency, I don't really see
> >>> the point of disabling it by default.
> >>
> >> Vop, hdmi and other video devices are also disabled.
> >> Follow the rest I think...
> > 
> > Well, these blocks do have related I/O ports so it makes sense not to enable
> > them by default because of pinmux, or because there might be no connector
> > populated/routed.
> > 
> > For a memory to memory internal block, I don't see any reason why.
> > It's definitely not board-specific and having to add these nodes for every board
> > that has them is kind of a pain and might be overlooked. This will easily result
> > in the feature not being available for end users without having to change the
> > dt.
> > 
> > Also, the vpu node is always enabled on rockchip (and sunxi) platforms.
> > I think these are better examples to follow.
> 
> From PX30 TRM-Part1:
> 
> Power domain is shared by vop and dsi.
> It's up to the user what blocks he/she enables and what power it uses.
> 
> PD_VO: VOP_M, VOP_S, RGA and DSI

Hum, there is no direct correlation between "node is enabled in dt" and "related
hardware block consumes power". And removing nodes from dt is certainly not an
appropriate way to do power management! Device-tree is a way to represent the
hardware, not a configuration interface (well, besides the /chosen node).

Besides, the RGA driver seems to have good runtime pm support, so be assured
that its clocks will be off when unused.

Cheers,

Paul

> > 
> > Cheers,
> > 
> > Paul
> > 
> >>>
> >>> What do you think?
> >>>
> >>> Cheers,
> >>>
> >>> Paul
> >>>
> >>>>> +	};
> >>>>> +
> >>>>>  	qos_gmac: qos@...18000 {
> >>>>>  		compatible = "syscon";
> >>>>>  		reg = <0x0 0xff518000 0x0 0x20>;
> >>>>>
> >>>>
> >>>
> >>
> > 
> 

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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