[PATCH] imx: dts: tbs2910: add u-boot dtsi to shrink image size

[Tom Rini <trini@konsulko.com>]

On Fri, Dec 06, 2019 at 11:03:17PM +0100, Heinrich Schuchardt wrote:
> On 12/6/19 8:26 PM, Soeren Moch wrote:
> > 
> > 
> > On 06.12.19 19:43, Tom Rini wrote:
> > > On Fri, Dec 06, 2019 at 07:30:47PM +0100, Anatolij Gustschin wrote:
> > > 
> > > > Use U-Boot specific board dtsi to remove some not used nodes and
> > > > properties. With this change applied considerable size reduction
> > > > has been observed:
> > > > 
> > > >    $ ./tools/buildman/buildman -b tbs2910 -f tbs2910 || \
> > > >      ./tools/buildman/buildman -b tbs2910 -sS tbs2910
> > > >    ...
> > > >    Summary of 2 commits for 1 boards (1 thread, 12 jobs per thread)
> > > >    01: Merge branch '2019-12-05-master-imports'
> > > >           arm:  w+   tbs2910
> > > >    02: imx: dts: tbs2910: add u-boot dtsi to shrink image size
> > > >           arm: (for 1/1 boards) all -24448.0 text -24448.0
> > > > 
> > > > Signed-off-by: Anatolij Gustschin <agust@denx.de>
> > > > ---
> > > > This patch was only build-tested, maybe this removes to much
> > > > and needs some tweaking. I'd appreciate if someone could test
> > > > it on actual hardware and finish the work, so we hopefully
> > > > can solve frequent CI build breakage caused by this target.
> > > > 
> > > >   arch/arm/dts/imx6q-tbs2910-u-boot.dtsi | 219 +++++++++++++++++++++++++
> > > >   1 file changed, 219 insertions(+)
> > > >   create mode 100644 arch/arm/dts/imx6q-tbs2910-u-boot.dtsi
> > > > 
> > > > diff --git a/arch/arm/dts/imx6q-tbs2910-u-boot.dtsi b/arch/arm/dts/imx6q-tbs2910-u-boot.dtsi
> > > > new file mode 100644
> > > > index 0000000000..3e9307f17f
> > > > --- /dev/null
> > > > +++ b/arch/arm/dts/imx6q-tbs2910-u-boot.dtsi
> > > > @@ -0,0 +1,219 @@
> > > > +// SPDX-License-Identifier: GPL-2.0+
> > > > +/*
> > > > + * U-Boot specific modifications for original tbs2910 DTS.
> > > > + * This drops not used nodes/properties to reduce the image size.
> > > > + */
> > > > +
> > > > +/ {
> > > > +	/delete-property/ model;
> > > > +	/delete-property/ compatible;
> > > > +
> > > > +	aliases {
> > > > +		/delete-property/ can0;
> > > > +		/delete-property/ can1;
> > > > +		/delete-property/ gpio3;
> > > > +		/delete-property/ gpio4;
> > > > +		/delete-property/ gpio5;
> > > > +		/delete-property/ ipu1;
> > > > +		/delete-property/ mmc3;
> > > > +		/delete-property/ spi0;
> > > > +		/delete-property/ spi1;
> > > > +		/delete-property/ spi2;
> > > > +		/delete-property/ spi3;
> > > > +		/delete-property/ spi4;
> > > > +		/delete-property/ serial2;
> > > > +		/delete-property/ serial3;
> > > > +		/delete-property/ serial4;
> > > > +		/delete-property/ video1;
> > > > +	};
> > > > +
> > > > +	/delete-node/ cpus;
> > > > +	/delete-node/ capture-subsystem;
> > > > +	/delete-node/ chosen;
> > > > +	/delete-node/ display-subsystem;
> > > > +	/delete-node/ fan;
> > > > +	/delete-node/ ir_recv;
> > > > +	/delete-node/ leds;
> > > > +	/delete-node/ memory;
> > > > +	/delete-node/ sound-sgtl5000;
> > > > +	/delete-node/ sound-spdif;
> > > > +
> > > > +	soc {
> > > > +		u-boot,dm-pre-reloc;
> > > > +		/delete-property/ ranges;
> > > > +		/delete-node/ timer at a00600;
> > > > +
> > > > +		aips-bus at 2000000 {
> > > > +			/delete-property/ ranges;
> > > > +			/delete-node/ aipstz at 207c000;
> > > > +			spba-bus at 2000000 {
> > > > +				/delete-property/ ranges;
> > > > +				/delete-node/ spba at 203c000;
> > > > +			};
> > > > +		};
> > > > +
> > > > +		aips-bus at 2100000 {
> > > > +			/delete-property/ ranges;
> > > > +			/delete-node/ aipstz at 217c000;
> > > > +			/delete-node/ mlb at 218c000;
> > > > +			/delete-node/ romcp at 21ac000;
> > > > +			/delete-node/ tzasc at 21d0000;
> > > > +			/delete-node/ tzasc at 21d4000;
> > > > +			/delete-node/ vdoa at 21e4000;
> > > > +		};
> > > > +	};
> > > > +};
> > > > +
> > > > +&anatop {
> > > > +	/delete-node/ regulator-1p1;
> > > > +	/delete-node/ regulator-2p5;
> > > > +	/delete-node/ regulator-3p0;
> > > > +	/delete-node/ regulator-vddcore;
> > > > +	/delete-node/ regulator-vddpu;
> > > > +	/delete-node/ regulator-vddsoc;
> > > > +};
> > > > +
> > > > +&sata {
> > > > +	/delete-property/ clocks;
> > > > +	/delete-property/ clock-names;
> > > > +	/delete-property/ interrupts;
> > > > +	/delete-property/ interrupts;
> > > > +	/delete-property/ fsl,transmit-level-mV;
> > > > +	/delete-property/ fsl,transmit-boost-mdB;
> > > > +	/delete-property/ fsl,transmit-atten-16ths;
> > > > +	/delete-property/ fsl,receive-eq-mdB;
> > > > +};
> > > > +
> > > > +&pcie {
> > > > +	/delete-property/ reg-names;
> > > > +	/delete-property/ device_type;
> > > > +	/delete-property/ bus-range;
> > > > +	/delete-property/ ranges;
> > > > +	/delete-property/ num-lanes;
> > > > +	/delete-property/ interrupts;
> > > > +	/delete-property/ interrupt-names;
> > > > +	/delete-property/ #interrupt-cells;
> > > > +	/delete-property/ interrupt-map-mask;
> > > > +	/delete-property/ interrupt-map;
> > > > +	/delete-property/ clocks;
> > > > +	/delete-property/ clock-names;
> > > > +};
> > > > +
> > > > +&uart1 {
> > > > +	/delete-property/ interrupts;
> > > > +	/delete-property/ clocks;
> > > > +	/delete-property/ clock-names;
> > > > +	/delete-property/ dmas;
> > > > +	/delete-property/ dma-names;
> > > > +};
> > > > +
> > > > +&uart2 {
> > > > +	/delete-property/ interrupts;
> > > > +	/delete-property/ clocks;
> > > > +	/delete-property/ clock-names;
> > > > +	/delete-property/ dmas;
> > > > +	/delete-property/ dma-names;
> > > > +};
> > > > +
> > > > +/delete-node/ &L2;
> > > > +/delete-node/ &asrc;
> > > > +/delete-node/ &audmux;
> > > > +/delete-node/ &can1;
> > > > +/delete-node/ &can2;
> > > > +/delete-node/ &crypto;
> > > > +/delete-node/ &dcic1;
> > > > +/delete-node/ &dcic2;
> > > > +/delete-node/ &dma_apbh;
> > > > +/delete-node/ &ecspi1;
> > > > +/delete-node/ &ecspi2;
> > > > +/delete-node/ &ecspi3;
> > > > +/delete-node/ &ecspi4;
> > > > +/delete-node/ &ecspi5;
> > > > +/delete-node/ &epit1;
> > > > +/delete-node/ &epit2;
> > > > +/delete-node/ &esai;
> > > > +/delete-node/ &gpt;
> > > > +/delete-node/ &gpio4;
> > > > +/delete-node/ &gpio5;
> > > > +/delete-node/ &gpio6;
> > > > +/delete-node/ &gpu_3d;
> > > > +/delete-node/ &gpu_2d;
> > > > +/delete-node/ &gpu_vg;
> > > > +/delete-node/ &gpmi;
> > > > +/delete-node/ &ipu2;
> > > > +/delete-node/ &kpp;
> > > > +/delete-node/ &ldb;
> > > > +/delete-node/ &mipi_csi;
> > > > +/delete-node/ &mmdc0;
> > > > +/delete-node/ &mmdc1;
> > > > +/delete-node/ &ocotp;
> > > > +/delete-node/ &ocram;
> > > > +/delete-node/ &pinctrl_gpio_fan;
> > > > +/delete-node/ &pinctrl_ir;
> > > > +/delete-node/ &pinctrl_gpio_leds;
> > > > +/delete-node/ &pinctrl_sgtl5000;
> > > > +/delete-node/ &pinctrl_spdif;
> > > > +/delete-node/ &pmu;
> > > > +/delete-node/ &pwm1;
> > > > +/delete-node/ &pwm2;
> > > > +/delete-node/ &pwm3;
> > > > +/delete-node/ &pwm4;
> > > > +/delete-node/ &sdma;
> > > > +/delete-node/ &reg_2p5v;
> > > > +/delete-node/ &sgtl5000;
> > > > +/delete-node/ &snvs;
> > > > +/delete-node/ &spdif;
> > > > +/delete-node/ &src;
> > > > +/delete-node/ &ssi1;
> > > > +/delete-node/ &ssi2;
> > > > +/delete-node/ &ssi3;
> > > > +/delete-node/ &tempmon;
> > > > +/delete-node/ &uart3;
> > > > +/delete-node/ &uart4;
> > > > +/delete-node/ &uart5;
> > > > +/delete-node/ &usbh2;
> > > > +/delete-node/ &usbh3;
> > > > +/delete-node/ &usdhc1;
> > > > +/delete-node/ &vpu;
> > > > +/delete-node/ &wdog2;
> > > > +/delete-node/ &weim;
> > > > +
> > > > +&gpr {
> > > > +	/delete-node/ ipu1_csi0_mux;
> > > > +	/delete-node/ ipu2_csi1_mux;
> > > > +};
> > > > +
> > > > +&gpc {
> > > > +	/delete-node/ pgc;
> > > > +};
> > > > +
> > > > +&hdmi {
> > > > +	/delete-node/ port at 2;
> > > > +	/delete-node/ port at 3;
> > > > +};
> > > > +
> > > > +&mipi_dsi {
> > > > +	ports {
> > > > +		/delete-node/ port at 2;
> > > > +		/delete-node/ port at 3;
> > > > +	};
> > > > +};
> > > > +
> > > > +&ipu1 {
> > > > +	u-boot,dm-pre-reloc;
> > > > +	/delete-property/ interrupts;
> > > > +	/delete-property/ clocks;
> > > > +	/delete-property/ clock-names;
> > > > +	/delete-property/ resets;
> > > > +	/delete-node/ port at 0;
> > > > +	/delete-node/ port at 1;
> > > > +
> > > > +	port at 2 {
> > > > +		/delete-node/ endpoint at 3;
> > > > +		/delete-node/ endpoint at 4;
> > > > +	};
> > > > +	port at 3 {
> > > > +		/delete-node/ endpoint at 3;
> > > > +		/delete-node/ endpoint at 4;
> > > > +	};
> > > > +};
> > Oh, most of the deleted properties and nodes are not defined in the
> > board dts, but in the soc dtsi instead.
> > So for me it would make more sense to also split the "delete dtsi" in a
> > board and soc part, if this really is the way to go.
> > > This gets an important conversation started.  Perhaps we should expand
> > > OF_SPL_REMOVE_PROPS for full U-Boot, with some gating symbol for the
> > > platforms that do want to pass through the full DT to the OS?
> > > 
> > I also already looked at OF_SPL_REMOVE_PROPS, would make much sense to
> > have this for full u-boot. To duplicate each device tree with an almost
> > identical "delete dtsi" looks like a huge maintenance burden for me.
> > 
> > Maybe the build system can at least automatically remove disabled nodes
> > and nodes without compatible in enabled DM drivers. This would not help
> > for unneeded properties in enabled nodes, but probably automatically
> > give the biggest part of size reduction.
> > 
> 
> In an ideal world the firmware and not the operating system would supply
> the device tree for booting the operating system. Currently for many
> boards the U-Boot supplied device tree is enough to boot Linux. Deleting
> nodes not used by U-Boot would not be helpful in this context.

Some boards today ship a DTB file.  Some more boards in the future may.
Some existing boards might even figure they want to.  But, some existing
boards will not want to.  If at some future point tbs2910 switches to
"lets put the DTB on flash somewhere", it will need sorting.  But for
now this seems like a reasonable path forward for existing hardware.

> 
> Best regards
> 
> Heinrich

-- 
Tom
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