[U-Boot] imx6 devices failing to build with 2016.05

[Stefano Babic]

Hi Peter,

On 27/04/2016 12:15, Peter Robinson wrote:
> Hi All,
> 
> I didn't look closely when it happened with rc1 because I saw a pull
> req from Stefano shortly afterwards and I decided to try again after
> that landed. With rc3 I'm still seeing the same issue.
> 
> Basically all the i.MX6 devices
> (cm_fx6,mx6cuboxi,novena,riotboard,udoo,wandboard,warp) we currently
> build for Fedora are failing to build. It looks very similar to some
> 64 bit math issues [1] [2] a search gives me although from the linker
> command I'm failing to see what code is at fault so any assistance in
> debugging this would be great. I've checked it failed on < gcc6 too
> and 2016.03 builds so it appears a regression in 05rcX.
> 
> The (for cuboxi example) basic error is:
>   ld.bfd   -pie  --gc-sections -Bstatic -Ttext 0x17800000 -o u-boot -T
> u-boot.lds arch/arm/cpu/armv7/start.o --start-group
> arch/arm/cpu/built-in.o  arch/arm/cpu/armv7/built-in.o
> arch/arm/imx-common/built-in.o  arch/arm/lib/built-in.o
> board/solidrun/mx6cuboxi/built-in.o  cmd/built-in.o  common/built-in.o
>  disk/built-in.o  drivers/built-in.o  drivers/dma/built-in.o
> drivers/gpio/built-in.o  drivers/i2c/built-in.o
> drivers/mmc/built-in.o  drivers/mtd/built-in.o
> drivers/mtd/onenand/built-in.o  drivers/mtd/spi/built-in.o
> drivers/net/built-in.o  drivers/net/phy/built-in.o
> drivers/pci/built-in.o  drivers/power/built-in.o
> drivers/power/battery/built-in.o  drivers/power/fuel_gauge/built-in.o
> drivers/power/mfd/built-in.o  drivers/power/pmic/built-in.o
> drivers/power/regulator/built-in.o  drivers/serial/built-in.o
> drivers/spi/built-in.o  drivers/usb/common/built-in.o
> drivers/usb/dwc3/built-in.o  drivers/usb/emul/built-in.o
> drivers/usb/eth/built-in.o  drivers/usb/gadget/built-in.o
> drivers/usb/gadget/udc/built-in.o  drivers/usb/host/built-in.o
> drivers/usb/musb-new/built-in.o  drivers/usb/musb/built-in.o
> drivers/usb/phy/built-in.o  drivers/usb/ulpi/built-in.o  fs/built-in.o
>  lib/built-in.o  net/built-in.o  test/built-in.o  test/dm/built-in.o
> --end-group arch/arm/lib/eabi_compat.o  -L
> /usr/lib/gcc/armv7hl-redhat-linux-gnueabi/6.0.0 -lgcc -Map u-boot.map
> ld.bfd: error: /usr/lib/gcc/armv7hl-redhat-linux-gnueabi/6.0.0/libgcc.a(_udivmoddi4.o)
> uses VFP register arguments, u-boot does not
> ld.bfd: failed to merge target specific data of file
> /usr/lib/gcc/armv7hl-redhat-linux-gnueabi/6.0.0/libgcc.a(_udivmoddi4.o)
> 
> Full log at https://pbrobinson.fedorapeople.org/u-boot-mx6cuboxi-fail.txt
> 

I can confirm this - I started bisect and I have found this one:

commit 3cb4f25cc702db17455583599d0940c81337a17a
Author: Peng Fan <van.freenix at gmail.com>
Date:   Wed Mar 9 16:07:21 2016 +0800

    video: ipu: avoid overflow issue

    Multiplication, as "clk->parent->rate * 16" may overflow. So use
    do_div to avoid such issue.

    Signed-off-by: Peng Fan <van.freenix at gmail.com>
    Signed-off-by: Sandor Yu <sandor.yu at nxp.com>
    Cc: Anatolij Gustschin <agust at denx.de>
    Cc: Stefano Babic <sbabic at denx.de>
    Cc: Fabio Estevam <fabio.estevam at nxp.com>

:040000 040000 9672cb921a1051b5357931e8835884e2cccf8ec6
3cbbeea448780bb4855f5458dd98d017239b729a M	drivers


Checking the patch, I have found:

clk->rate = (u64)(clk->parent->rate * 16) / div;


This seems the cause for the failing build.

This confirms an issue. IMHO we can replace it with:

clk->rate = (u64)lldiv(clk->parent->rate * 16, div);

Peng, what do you mind ?

Best regards,
Stefano Babic

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