linux-kernel - Re: [PATCH 3/6] ARM: dts: sunxi: h3/h5: Add MBUS controller node

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Message-ID: <1679881.yZ8pMUtPNZ@jernej-laptop>
Date:   Thu, 12 Sep 2019 22:28:37 +0200
From:   Jernej Škrabec <jernej.skrabec@...l.net>
To:     Maxime Ripard <mripard@...nel.org>
Cc:     wens@...e.org, robh+dt@...nel.org, mark.rutland@....com,
        mchehab@...nel.org, hverkuil@...all.nl, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 3/6] ARM: dts: sunxi: h3/h5: Add MBUS controller node

Dne četrtek, 12. september 2019 ob 22:20:57 CEST je Maxime Ripard napisal(a):
> Hi,
> 
> On Thu, Sep 12, 2019 at 07:51:29PM +0200, Jernej Skrabec wrote:
> > Both, H3 and H5, contain MBUS, which is the bus used by DMA devices to
> > access system memory.
> > 
> > MBUS controller is responsible for arbitration between channels based
> > on set priority and can do some other things as well, like report
> > bandwidth used. It also maps RAM region to different address than CPU.
> > 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
> > ---
> > 
> >  arch/arm/boot/dts/sunxi-h3-h5.dtsi | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/sunxi-h3-h5.dtsi
> > b/arch/arm/boot/dts/sunxi-h3-h5.dtsi index eba190b3f9de..ef1d03812636
> > 100644
> > --- a/arch/arm/boot/dts/sunxi-h3-h5.dtsi
> > +++ b/arch/arm/boot/dts/sunxi-h3-h5.dtsi
> > @@ -109,6 +109,7 @@
> > 
> >  		compatible = "simple-bus";
> >  		#address-cells = <1>;
> >  		#size-cells = <1>;
> > 
> > +		dma-ranges;
> > 
> >  		ranges;
> >  		
> >  		display_clocks: clock@...0000 {
> > 
> > @@ -538,6 +539,14 @@
> > 
> >  			};
> >  		
> >  		};
> > 
> > +		mbus: dram-controller@...2000 {
> > +			compatible = "allwinner,sun8i-h3-mbus";
> > +			reg = <0x01c62000 0x1000>;
> > +			clocks = <&ccu 113>;
> > +			dma-ranges = <0x00000000 0x40000000 
0xc0000000>;
> > +			#interconnect-cells = <1>;
> > +		};
> > +
> 
> If that's easy enough to access, can you also add the references in
> the devices that are already there? (CSI and DE comes to my mind, but
> there might be others).

Strangely, DE2 doesn't use this offset. That was tested on OrangePi Plus2E, 
which has 2 GiB of RAM and subtracting this offset causes corrupted image.

But I can add this properties to CSI too. However, wouldn't that need CSI DT 
binding expansion with those properties? othetwise DT check will fail.

Best regards,
Jernej

> 
> Thanks!
> Maxime