Re: [PATCH v5 4/5] ARM: dts: mt8135: enable basic SMP bringup for mt8135

[Eddie Huang <eddie.huang@mediatek.com>]

On Thu, 2015-11-12 at 15:56 -0800, Kevin Hilman wrote:
> Eddie Huang <eddie.huang@mediatek.com> writes:
> 
> > On Wed, 2015-11-11 at 20:54 -0800, Kevin Hilman wrote:
> >> Hi Eddie,
> >> 
> >> Kevin Hilman <khilman@kernel.org> writes:
> >> 
> >> > Eddie Huang <eddie.huang@mediatek.com> writes:
> >> >
> >> >> On Tue, 2015-11-10 at 17:16 -0800, Kevin Hilman wrote:
> >> >>> Hi Eddie,
> >> >>> 
> >> >>> [...]
> >> >>> 
> >> >>> > I check the log [0],
> >> >>> 
> >> >>> Thanks for checking into this boot failure.
> >> >>> 
> >> >>> > it seems first time mt8135-evbp1 boot to kernel
> >> >>> > shell successfully, then boot again. In the second time, mt8135 stay in
> >> >>> > fastboot mode, waiting host send boot image, then timeout.
> >> >>> 
> >> >>> Actually, it never gets to a shell the first time.  If you look closely,
> >> >>> the target reboots as soon as userspace starts.   Look for the PYBOOT
> >> >>> line which says "finished booting, starting userspace"
> >> >>> 
> >> >>> Later on, pyboot thinks it finds a root shell due to finding '#'
> >> >>> characters, but clearly it never got to a shell.
> >> >>> 
> >> >>> > I download zImage and dtb in [1], and kernel run to shell successfully
> >> >>> > on my platform.
> >> >>> 
> >> >>> Are you can you try using a ramdisk as well?  You can use the pre-built
> >> >>> one here:
> >> >>> http://storage.kernelci.org/images/rootfs/buildroot/armel/rootfs.cpio.gz
> >> >>> 
> >> >>
> >> >> Yes, I tried this ramdisk, and I can reproduce fail issue.
> >> >>
> >> >
> >> > OK, good.   Thanks for looking into it.
> >> >
> >> >>> Please check my boot logs to see how I'm generating the boot.img file
> >> >>> (search for mkbootimg) with a kernel/dtb/ramdisk.  It may be possible
> >> >>> that the kernel image size with a ramdisk is breaking some of the
> >> >>> assumptions in the fastboot mode.  I've seen problems like this on other
> >> >>> platforms due to hard-coded sizes/addresses in the boot firmware.
> >> >>> 
> >> >>
> >> >> MT8135 allocate 10MB for BOOT partition, but the test boot.img is 11MB,
> >> >> thus cause user space fail.
> >> >
> >> > Aha, I was right!  ;)
> >> 
> >> Also notice in kernelci.org that the mt8173 board has also been failing
> >> to boot in mainline[1].  I wonder if this same limitation exists in the
> >> mt8173 boot firmware?
> >> 
> >
> > MT8173 is another case, the failure is due to following commit:
> > 67e56c5 arm64: dts: mt8173: Add subsystem clock controller device nodes
> >
> > It is because this commit register MM subsystem clock, but kernel don't
> > use MM clock yet, then CCF disable it. (My internal platform kernel
> > command include clk_ignore_unused parameter, so don't have this
> > problem).I will do further checking and release solution later. Thanks
> > your testing.
> 
> OK, thanks for looking into it.
> 
> However, since the merge window is very close to closing, unless you can
> git a fix out soon (and one that doesn't introduce other bugs),
> probablly the right solution is to just revert the above patch so things
> are fixed for mainline ASAP.
> 

I send one patch to fix this problem. Hope this patch can apply to 4.4.

http://lists.infradead.org/pipermail/linux-arm-kernel/2015-November/384800.html

Eddie
Thanks