Re: [Buildroot] [PATCH v2 1/1] board/xilinx: bump to linux 6.6.40

[Luca Ceresoli via buildroot <buildroot@buildroot.org>]

Hello Nea, Michal, Brandon, Thomas, Peter,

On Fri, 9 Aug 2024 15:19:30 +0000
"Frager, Neal" <neal.frager@amd.com> wrote:

> Hi Brandon,
> 
> > Hi Brandon,
> >  
> > > This patch bumps all Xilinx board defconfigs to Linux 6.6.40.
> > >
> > > Xilinx Evaluation Boards:
> > > configs/versal_vck190_defconfig
> > > configs/versal_vpk180_defconfig
> > > configs/zynq_microzed_defconfig
> > > configs/zynq_zc702_defconfig
> > > configs/zynq_zc706_defconfig
> > > configs/zynq_zed_defconfig
> > > configs/zynqmp_kria_kd240_defconfig
> > > configs/zynqmp_kria_kr260_defconfig
> > > configs/zynqmp_kria_kv260_defconfig
> > > configs/zynqmp_zcu102_defconfig
> > > configs/zynqmp_zcu104_defconfig
> > > configs/zynqmp_zcu106_defconfig  
> >  
> > > I attempted to boot this patch on a zcu106, but I get no output over the
> > > uart port from anything, U-Boot SPL, ATF, etc. So this board may be
> > > broken on master.  
> >  
> > > Can you verify if it works on your end?  
> >
> > I can help you with this problem.  It is because there are two different
> > versions of the zcu106 having different DDR memories.  This is because the
> > DDR that came on the revA version of the board became obsolete.
> >
> > I left the revA device tree in buildroot as I know this is the version of the
> > zcu106 that Peter Korsgaard has.  Based on your comment, I believe you have
> > the newer version of the zcu106.
> >
> > To fix this, only the u-boot psu_init_gpl.c needs to be changed, so the
> > correct spl psu_init routine will run.
> >
> > Please implement the following in your zcu106 defconfig:
> >
> > - BR2_TARGET_UBOOT_CUSTOM_MAKEOPTS="DEVICE_TREE=zynqmp-zcu106-revA
> > + BR2_TARGET_UBOOT_CUSTOM_MAKEOPTS="DEVICE_TREE=zynqmp-zcu106-rev1.0
> >
> > This will build in the correct psu_init_gpl.c from the two choices below:
> > https://github.com/Xilinx/u-boot-xlnx/tree/master/board/xilinx/zynqmp/zynqmp-zcu106-rev1.0
> > https://github.com/Xilinx/u-boot-xlnx/tree/master/board/xilinx/zynqmp/zynqmp-zcu106-revA
> >
> > You can read about this issue for the zcu102 and zcu106 here:
> > https://support.xilinx.com/s/article/71961?language=en_US  
> 
> > Thank you! Switching to the rev1.0 devicetree does let my board boot.  
> 
> Great!
> 
> >
> > Do you have any opinions for how this can be better handled in buildroot to
> > support both versions of the zcu102 and zcu106?  
> 
> > My preference would be to having two defconfigs, as they are effectively
> > different boards. But given Thomas would prefer not adding new
> > defconfigs, documenting it in the defconfig as you did is a good idea.  
> 
> As I mentioned in my previous response, I will move this documentation to the
> readme.txt file.  It makes more sense there.

I agree the readme file seems the most appropriate.

> > At the moment, the older version of the zcu106 is supported and the newer
> > version of the zcu102 is supported in buildroot natively.  
> 
> > Would it be prudent to default the zcu106 to the newest revision? Is
> > there any idea of if the zcu106 revA or rev1.0 is more widely used?  
> 
> Now that I think about it, you are absolutely right.  Not only are all new
> boards using the rev1.0 DDR memories, but I have to believe the vast majority
> of boards out there are on the new memory at this point.
> 
> The only reason I kept the zcu106 on revA was because I knew that Peter's
> zcu106 has revA DDR memory.  That is probably not the best reason to keep the
> zcu106 defconfig on revA.  Sorry Peter!
> 
> So unless anyone objects, I plan to do the following.
> 
> 1. Migrate the zynqmp_zcu106_defconfig to rev1.0 DDR memory.
> 
> 2. Document the revA/rev1.0 issue in the board/zynqmp/readme.txt, so that
> users of the old boards have at least a chance of finding that they need to
> change the u-boot device_tree config for revA DDR memory.

Would it be possible to have a single psu_init_gpl.c that works for
both revisions, albeit with non-optimal performance for both? I don't
know what the differences are between the two revisions, but if it is a
matter of timings it should be possible.

Custom designs will use a custom psu_init_gpl.c anyway, so that
wouldn't affect performance of industrial products.

Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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