[U-Boot] [PATCHv2 2/3] ARMv8/layerscape: Add FSL PPA support

[Zhiqiang Hou]

Hi Rod and Chenhui,

Can you help to answer the questions about PSCI and PPA?

> -----Original Message-----
> From: Scott Wood [mailto:oss at buserror.net]
> Sent: 2016年1月23日 4:22
> To: york sun <york.sun at nxp.com>; Bhupesh Sharma <bhupesh.sharma at nxp.com>;
> Zhiqiang Hou <Zhiqiang.Hou at freescale.com>; u-boot at lists.denx.de;
> albert.u.boot at aribaud.net; Mingkai.hu at freescale.com; Stuart Yoder
> <stuart.yoder at nxp.com>; leoli at freescale.com; prabhakar at freescale.com;
> bhupesh.sharma at freescale.com; Zhiqiang Hou <zhiqiang.hou at nxp.com>
> Subject: Re: [PATCHv2 2/3] ARMv8/layerscape: Add FSL PPA support
> 
> On Fri, 2016-01-22 at 20:18 +0000, york sun wrote:
> > On 01/22/2016 12:14 PM, Bhupesh Sharma wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Scott Wood [mailto:oss at buserror.net]
> > > > Sent: Saturday, January 23, 2016 1:39 AM
> > > > To: york sun; Zhiqiang Hou; u-boot at lists.denx.de;
> > > > albert.u.boot at aribaud.net; Mingkai.hu at freescale.com; Stuart Yoder;
> > > > leoli at freescale.com; prabhakar at freescale.com;
> > > > bhupesh.sharma at freescale.com; Zhiqiang Hou
> > > > Subject: Re: [PATCHv2 2/3] ARMv8/layerscape: Add FSL PPA support
> > > >
> > > > On Fri, 2016-01-22 at 20:05 +0000, york sun wrote:
> > > > > On 01/21/2016 01:53 AM, Zhiqiang Hou wrote:
> > > > > > From: Hou Zhiqiang <Zhiqiang.Hou at freescale.com>
> > > > > >
> > > > > > The FSL Primary Protected Application (PPA) is a software
> > > > > > component loaded during boot which runs in TrustZone and
> > > > > > remains resident after boot.
> > > > > >
> > > > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou at freescale.com>
> > > > > > ---
> > > > > > Tested on LS1043A RDB board
> > > > > >
> > > > >
> > > > > I presume PSCI is implemented in PPA. How does the SMP boot flow
> > > > > change with PPA? U-boot has to remain functional in the absence
> > > > > of PPA,
> > > > right?
> > > > >
> > > > > Would it be possible to write a readme for PPA?
> > > >
> > > > Also, how does the devicetree get updated to indicate the presence
> > > > of PSCI?
> > > >
> > >
> > > One needs to add PSCI node in the DTS for the same, claiming support
> > > for PSCI specification.
> > > The cpu.enable_method needs to be changed from spin-table to psci as well.
> > >
> > > See
> > > http://lxr.free-electrons.com/source/Documentation/devicetree/bindin
> > > gs
> > > /arm/psci.txt for details.
> > >
> >
> > Bhupesh,
> >
> > Before PPA is fully adopted, u-boot has to detect the existence of PPA
> > and decide to use PSCI or spin table, right? So the device tree node
> > should also be fixed accordingly.
> 
> How would U-Boot know what version of PSCI the loaded PPA supports?  Is or
> could there be any metadata on the PPA image to convey such information?
> 

Thanks,
Zhiqiang