linux-kernel - New warnings with gcc-11

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Message-ID: <CAHk-=whOOVBBuQceJ9D9uZrv-QOUWGMQ4aZe2K+2X24o7xA8cg@mail.gmail.com>
Date:   Tue, 27 Apr 2021 16:43:54 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Dave Airlie <airlied@...il.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc:     Daniel Vetter <daniel.vetter@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: New warnings with gcc-11

I've updated to Fedora 34 on one of my machines, and it causes a lot
of i915 warnings like

  drivers/gpu/drm/i915/intel_pm.c: In function ‘ilk_setup_wm_latency’:
  drivers/gpu/drm/i915/intel_pm.c:3059:9: note: referencing argument 3
of type ‘const u16 *’ {aka ‘const short unsigned int *’}
  drivers/gpu/drm/i915/intel_pm.c:2994:13: note: in a call to function
‘intel_print_wm_latency’

and the reason is that gcc now seems to look at the argument array
size more, and notices that

 (a) intel_print_wm_latency() takes a "const u16 wm[8]" argument

but

 (b) most of the arrays passed in tend to look like 'u16 pri_latency[5]'

I think I will make the argument type to intel_print_wm_latency() be
just "const u16 wm[]" for now, just to avoid seeing a ton of silly
warnings.

I'm not sure if there is a better solution (like making all of those
latency arrays be 8 entries in size), so I'm just letting you know
about my change in this area in case anybody has a better idea.

             Linus