[U-Boot] [PATCH v2 07/11] imx: tpc70: dts: Add TPC70 board (imx6q based) device tree description

[Lukasz Majewski]

Hi Tom,

> On Sun, Aug 11, 2019 at 11:25:37PM +0200, Lukasz Majewski wrote:
> > Hi Peng,
> >   
> > > > Subject: [PATCH v2 07/11] imx: tpc70: dts: Add TPC70 board
> > > > (imx6q based) device tree description
> > > > 
> > > > This commit defines the TPC70 imx6q board with device tree
> > > > description.    
> > > 
> > > Is the imx6q-kp.dtsi usable for this board from Linux kernel?
> > >   
> > 
> > The imx6q-kp.dtsi is defined in the Linux kernel [1].
> > 
> > However, not all features - like backlight, CAN, etc. are needed in
> > U-Boot. To reduce SPL footprint, as the TPC70 is the first
> > board (from i.MX6Q family of SoCs) which uses only DM in SPL and
> > U-Boot proper, only the necessary subset of [1] was added to U-Boot.
> > 
> > Note:
> > 
> > [1] -
> > https://elixir.bootlin.com/linux/v5.2.8/source/arch/arm/boot/dts/imx6q-kp.dtsi
> >  
> 
> Right, and that's what we have CONFIG_OF_SPL_REMOVE_PROPS for, yes?
> 

Not quite. For example I need "clocks" property, which is defined for
almost all nodes. This incurs some extra cost in terms of footprint.

To reduce the SPL size (to which dtb file size contributes), I had to
not include full DTS from Linux in U-Boot.

I only used a subset of it (only _really_ necessary description to run
U-Boot) to reduce size of SPL binary.

Best regards,

Lukasz Majewski

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