[PATCH] drm/edid: Fix EDID quirk compile error on older compilers

[Sam Ravnborg]

On Fri, Sep 24, 2021 at 07:53:21AM -0700, Douglas Anderson wrote:
> Apparently some compilers [1] cannot handle doing math on dereferenced
> string constants at compile time. This has led to reports [2] of
> compile errors like:
> 
>   In file included from drivers/gpu/drm/drm_edid.c:42:0:
>   ./include/drm/drm_edid.h:525:2: error: initializer element is not constant
>     ((((u32)((vend)[0]) - '@') & 0x1f) << 26 | \
> 
> Go back to the syntax I used in v4 of the patch series [3] that added
> this code instead of what landed (v5). This syntax is slightly uglier
> but should be much more compatible with varied compilers.
> 
> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69960#c18
> [2] https://lore.kernel.org/r/874kaabdt5.fsf@intel.com/
> [3] https://lore.kernel.org/r/20210909135838.v4.4.I6103ce2b16e5e5a842b14c7022a034712b434609@changeid/
> 
> Fixes: d9f91a10c3e8 ("drm/edid: Allow querying/working with the panel ID from the EDID")
> Reported-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> Reported-by: Srikanth Myakam <smyakam at microsoft.com>
> Signed-off-by: Douglas Anderson <dianders at chromium.org>

Not so nice, but apparently needed.
Acked-by: Sam Ravnborg <sam at ravnborg.org>