Re: [kbuild-all] Re: [PATCH v2 9/9] drm/bridge: ti-sn65dsi86: Avoid invalid rates

From: Rong Chen
Date: Mon Jan 06 2020 - 19:55:50 EST




On 1/7/20 6:43 AM, Doug Anderson wrote:
Dear Robot,

On Sat, Dec 21, 2019 at 5:57 AM kbuild test robot <lkp@xxxxxxxxx> wrote:
Hi Douglas,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.5-rc2 next-20191220]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url: https://github.com/0day-ci/linux/commits/Douglas-Anderson/drm-bridge-ti-sn65dsi86-Improve-support-for-AUO-B116XAK01-other-DP/20191221-083448
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 7e0165b2f1a912a06e381e91f0f4e495f4ac3736
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gcc (GCC) 7.5.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.5.0 make.cross ARCH=sh

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

drivers/gpu/drm/bridge/ti-sn65dsi86.c: In function 'ti_sn_bridge_enable':
drivers/gpu/drm/bridge/ti-sn65dsi86.c:543:18: warning: 'rate_valid' may be used uninitialized in this function [-Wmaybe-uninitialized]
if (rate_valid[i])
~~~~~~~~~~^~~
I love your report! Interestingly I had already noticed this problem
myself and v3 of the patch fixes the issue. See:

https://lore.kernel.org/r/20191218143416.v3.9.Ib59207b66db377380d13748752d6fce5596462c5@changeid


If the maintainer of the robot is reading this, something to improve
about your robot is that it could have noticed v3 of the patch (which
was posted several days before your report) and skipped analyzing v2
of the patch. I'm currently using Change-Ids embedded in my
Message-Id to help automation relate one version of my patches to the
next. Specifically you compare the Message-Id of v2 and v3 of this
patch:

20191217164702.v2.9.Ib59207b66db377380d13748752d6fce5596462c5@changeid
20191218143416.v3.9.Ib59207b66db377380d13748752d6fce5596462c5@changeid

Since the last section before the "@changeid" remained constant it
could be assumed that this patch replaced the v2. I know there's not
too much usage of this technique yet, but if only more tools supported
it then maybe more people would use it.

Hi Doug,

Thanks for your suggestion, the root cause is that the v3 wasn't handled before this report.
We'll definitely give serious thought to your suggestion.

 v2: Douglas-Anderson/drm-bridge-ti-sn65dsi86-Improve-support-for-AUO-B116XAK01-other-DP/20191221-083448
 v3: Douglas-Anderson/drm-bridge-ti-sn65dsi86-Improve-support-for-AUO-B116XAK01-other-DP/20191222-062646

Best Regards,
Rong Chen



-Doug
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