[PATCH 4/6] arm64/ls1043a: add DTS for Freescale LS1043A SoC

[Hou Zhiqiang]

> -----Original Message-----
> From: Mark Rutland [mailto:mark.rutland at arm.com]
> Sent: 2015年9月23日 6:15
> To: Hou Zhiqiang-B48286
> Cc: Marc Zyngier; linux-arm-kernel at lists.infradead.org; Catalin Marinas;
> Will Deacon; linux-i2c at vger.kernel.org; linux-watchdog at vger.kernel.org;
> linux-doc at vger.kernel.org; linux-clk at vger.kernel.org; Xie Shaohui-B21989;
> corbet at lwn.net; Sharma Bhupesh-B45370; mturquette at baylibre.com; wsa at the-
> dreams.de; sboyd at codeaurora.org; wim at iguana.be; Song Wenbin-B53747; Wood
> Scott-B07421; Hu Mingkai-B21284; Li Yang-Leo-R58472
> Subject: Re: [PATCH 4/6] arm64/ls1043a: add DTS for Freescale LS1043A SoC
> 
> On Tue, Sep 22, 2015 at 10:50:21AM +0100, Hou Zhiqiang wrote:
> > Hi Mark,
> >
> > > -----Original Message-----
> > > From: Mark Rutland [mailto:mark.rutland at arm.com]
> > > Sent: 2015年9月22日 9:24
> > > To: Hou Zhiqiang-B48286; marc.zyngier at arm.com
> > > Cc: linux-arm-kernel at lists.infradead.org; Catalin Marinas; Will
> > > Deacon; linux-i2c at vger.kernel.org; linux-watchdog at vger.kernel.org;
> > > linux- doc at vger.kernel.org; linux-clk at vger.kernel.org; Xie
> > > Shaohui-B21989; corbet at lwn.net; Sharma Bhupesh-B45370;
> > > mturquette at baylibre.com; wsa at the- dreams.de; sboyd at codeaurora.org;
> > > wim at iguana.be; Song Wenbin-B53747; Wood Scott-B07421; Hu
> > > Mingkai-B21284; Li Yang-Leo-R58472
> > > Subject: Re: [PATCH 4/6] arm64/ls1043a: add DTS for Freescale
> > > LS1043A SoC
> > >
> > > Hi,
> > >
> > > > +/memreserve/ 0x80000000 0x00010000;
> > >
> > > Why is this necessary?
> >
> > This memory region is pre-reserved for the spin-table/psci, although
> > didn't add Enable method of secondary cores.
> 
> Your PSCI implementation isn't in secure memory?
> 

Sorry, this is for spin-table, psci will fix it in u-boot.

> > > > +       ifc: ifc at 1530000 {
> > > > +               compatible = "fsl,ifc", "simple-bus";
> > > > +               reg = <0x0 0x1530000 0x0 0x10000>;
> > > > +               interrupts = <0 43 0x4>;
> > > > +       };
> > >
> > > Why simple-bus?
> >
> > There are 3 child node located in dtsi file that should be created and
> > added to platform device list.
> 
> Are they usable even if the kernel knew nothing about the IFC node? If
> not, the IFC driver should probe them, and simple-bus should go.
> 
> > > > +       memory at 80000000 {
> > > > +               device_type = "memory";
> > > > +               reg = <0x0 0x80000000 0 0x80000000>;
> > > > +                     /* DRAM space 1 - 2 GB DRAM */
> > >
> > > I don't understand the comment. This describes 2GB at 2GB.
> > >
> >
> > Yes, there is a 2GB space for DRAM from address 2G.
> > The DRAM address 0x0 will be remapped to SoC address 2G, this remap is
> done by hardware.
> 
> I just realised my mistake -- I read this as "1 to 2 GB", when this is
> actually "DRAM space 1". Sorry for the noise.
> 

Thanks,
Zhiqiang