2019-12-14 13:04:48

by Russell King (Oracle)

[permalink] [raw]
Subject: Re: BUG - was: [GIT PULL 2/3] bcm2835-soc-next-2019-10-15

On Sat, Dec 14, 2019 at 11:54:19AM +0100, H. Nikolaus Schaller wrote:
> Hi Stefan,
>
> > Am 15.10.2019 um 19:15 schrieb Stefan Wahren <[email protected]>:
> >
> > Hi Florian,
> >
> > The following changes since commit 54ecb8f7028c5eb3d740bb82b0f1d90f2df63c5c:
> >
> > Linux 5.4-rc1 (2019-09-30 10:35:40 -0700)
> >
> > are available in the git repository at:
> >
> > git://github.com/anholt/linux tags/bcm2835-soc-next-2019-10-15
> >
> > for you to fetch changes up to 781fa0a954240c8487683ddf837fb2c4ede8e7ca:
> >
> > ARM: bcm: Add support for BCM2711 SoC (2019-10-10 19:21:03 +0200)
>
> this patch has finally arrived in v5.5-rc1 but it seems to break
> multiplatform build.
>
> We run a distribution kernel that supports OMAP3/4/5, i.MX6 and RasPi 3B+
> but since rebasing to v5.5-rc1 the kernel hangs after "Starting Kernel ...".
> On all ARM devices (incl. RasPi 3B+).
>
> Playing with our defconfig did show that deconfiguring CONFIG_ARCH_BCM2835
> makes the kernel work again.
>
> After further analysis it turns out that reverting this patch also
> makes the boards work again.
>
> I am not exactly sure what the reason is, but it may have something to
> do with the new auto-selection of CONFIG_ZONE_DMA which is not automatically
> selected by OMAP and i.MX6.
>
> To reproduce on some OMAP device (i.MX6 should be similar)
>
> 1st test:
>
> git checkout v5.5-rc1
> make omap2plus_defconfig
>
> => boots OMAP device
>
> 2nd test:
>
> ( echo CONFIG_ARCH_BCM2835=y; echo CONFIG_ARCH_BCM=y ) >>arch/arm/configs/omap2plus_defconfig
> make omap2plus_defconfig
>
> => fails to boot OMAP device
>
> 3rd test:
>
> git revert 781fa0a954240c8487683ddf837fb2c4ede8e7ca
> make omap2plus_defconfig
>
> => boots OMAP device
>
> BTW: the RasPi 3B+ runs equally well without this patch. So what is it
> good for?
>
> So please check and fix this patch.

Enabling ZONE_DMA shouldn't cause this problem - but as it does, please
enable memblock debugging and early console, and please send any boot
messages you can get from the system when it fails to boot. Also
having a successful boot log may be useful.

Thanks.

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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2019-12-14 15:56:38

by Andreas Kemnade

[permalink] [raw]
Subject: Re: [Letux-kernel] BUG - was: [GIT PULL 2/3] bcm2835-soc-next-2019-10-15

On Sat, 14 Dec 2019 12:59:47 +0000
Russell King - ARM Linux admin <[email protected]> wrote:

> On Sat, Dec 14, 2019 at 11:54:19AM +0100, H. Nikolaus Schaller wrote:
> > Hi Stefan,
> >
> > > Am 15.10.2019 um 19:15 schrieb Stefan Wahren <[email protected]>:
> > >
> > > Hi Florian,
> > >
> > > The following changes since commit 54ecb8f7028c5eb3d740bb82b0f1d90f2df63c5c:
> > >
> > > Linux 5.4-rc1 (2019-09-30 10:35:40 -0700)
> > >
> > > are available in the git repository at:
> > >
> > > git://github.com/anholt/linux tags/bcm2835-soc-next-2019-10-15
> > >
> > > for you to fetch changes up to 781fa0a954240c8487683ddf837fb2c4ede8e7ca:
> > >
> > > ARM: bcm: Add support for BCM2711 SoC (2019-10-10 19:21:03 +0200)
> >
> > this patch has finally arrived in v5.5-rc1 but it seems to break
> > multiplatform build.
> >
> > We run a distribution kernel that supports OMAP3/4/5, i.MX6 and RasPi 3B+
> > but since rebasing to v5.5-rc1 the kernel hangs after "Starting Kernel ...".
> > On all ARM devices (incl. RasPi 3B+).
> >
> > Playing with our defconfig did show that deconfiguring CONFIG_ARCH_BCM2835
> > makes the kernel work again.
> >
> > After further analysis it turns out that reverting this patch also
> > makes the boards work again.
> >
> > I am not exactly sure what the reason is, but it may have something to
> > do with the new auto-selection of CONFIG_ZONE_DMA which is not automatically
> > selected by OMAP and i.MX6.
> >
> > To reproduce on some OMAP device (i.MX6 should be similar)
> >
> > 1st test:
> >
> > git checkout v5.5-rc1
> > make omap2plus_defconfig
> >
> > => boots OMAP device
> >
> > 2nd test:
> >
> > ( echo CONFIG_ARCH_BCM2835=y; echo CONFIG_ARCH_BCM=y ) >>arch/arm/configs/omap2plus_defconfig
> > make omap2plus_defconfig
> >
> > => fails to boot OMAP device
> >
here it does not give any output at all if earlycon is appended to
kernel parameters.

> > 3rd test:
> >
> > git revert 781fa0a954240c8487683ddf837fb2c4ede8e7ca
> > make omap2plus_defconfig
> >
> > => boots OMAP device
> >
> > BTW: the RasPi 3B+ runs equally well without this patch. So what is it
> > good for?
> >
> > So please check and fix this patch.
>
> Enabling ZONE_DMA shouldn't cause this problem - but as it does, please
> enable memblock debugging and early console, and please send any boot
> messages you can get from the system when it fails to boot. Also
> having a successful boot log may be useful.
>
diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index ad08d470a2ca..b46cf3d5e389 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -17,6 +17,7 @@ config ARCH_OMAP3
select OMAP_INTERCONNECT
select PM_OPP if PM
select PM if CPU_IDLE
+ select ZONE_DMA
select SOC_HAS_OMAP2_SDRC
select ARM_ERRATA_430973

seems not to cause problems with make omap2plus_defconfig
here.

Regards,
Andreas