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

[Kevin Hilman]

Eddie Huang <eddie.huang at mediatek.com> writes:

> On Wed, 2015-11-11 at 20:54 -0800, Kevin Hilman wrote:
>> Hi Eddie,
>> 
>> Kevin Hilman <khilman at kernel.org> writes:
>> 
>> > Eddie Huang <eddie.huang at 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.

Kevin