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

From: Kevin Hilman <khilman@kernel.org>
To: Eddie Huang <eddie.huang@mediatek.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>,
	"devicetree\@vger.kernel.org" <devicetree@vger.kernel.org>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	<srv_heupstream@mediatek.com>, Arnd Bergmann <arnd@arndb.de>,
	Tyler Baker <tyler.baker@linaro.org>,
	Stephen Boyd <sboyd@codeaurora.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Olof Johansson <olof@lixom.net>, Rob Herring <robh+dt@kernel.org>,
	<linux-mediatek@lists.infradead.org>,
	Sascha Hauer <kernel@pengutronix.de>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	"linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v5 4/5] ARM: dts: mt8135: enable basic SMP bringup for mt8135
Date: Tue, 10 Nov 2015 17:16:42 -0800	[thread overview]
Message-ID: <7h1tbx1gjp.fsf@deeprootsystems.com> (raw)
In-Reply-To: <1447135867.14454.9.camel@mtksdaap41> (Eddie Huang's message of "Tue, 10 Nov 2015 14:11:07 +0800")

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

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.

> I don't know whether this issue caused by test environment or not.

I do not think it is the test environment, since as you can see from
[1], it's booting just fine with mainline kernel, and was working fine
until next-20151102.

Kevin

[1] http://kernelci.org/boot/mt8135-evbp1/job/next/kernel/next-20151110/defconfig/multi_v7_defconfig/lab/lab-khilman/?_id=5642652759b5149878091908