Re: [PATCH] video: fbdev: matroxfb: remove dead code and set but not used variable

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Wed, Apr 08, 2020 at 10:18:52AM +0000, Sam Ravnborg wrote:
> On Fri, Apr 03, 2020 at 10:16:09AM +0800, Jason Yan wrote:
> > Fix the following gcc warning:
> > 
> > drivers/video/fbdev/matrox/g450_pll.c:336:15: warning: variable
> > ‘pixel_vco’ set but not used [-Wunused-but-set-variable]
> >   unsigned int pixel_vco;
> >                ^~~~~~~~~
> > 
> > Reported-by: Hulk Robot <hulkci@huawei.com>
> > Signed-off-by: Jason Yan <yanaijie@huawei.com>
> 
> Thanks, committed and pushed to drm-misc-next.
> The fix will show up in upstream kernel at the next
> merge window.

The most of the patches from so called Hulk Robot appeared to be controversial.

First of all, even so called "dead code" may have side effects on the registers
in HW which may lead to other issues. Second, the mentioned dead code elimination
patch doesn't improve anything as now the dead code is 'mnp' variable (that's how
I got into that, I still have a build error).

That said, for the starter I suggest to revert this change. After one need go
carefully through code to understand if it's exactly the case and what to do with
'mnp' which involves some IO.

+Cc: current fbdev maintainers

-- 
With Best Regards,
Andy Shevchenko