[PATCH] drm/amd/display: Add comment for NaN checks in DCN calcs

[Harry Wentland]

On 2017-10-12 03:32 AM, Nils Wallménius wrote:
> Hi Harry, couldn't a simple isnan() macro be used? Also a question below.
> 

Both very good points. I'll send a new patch.

Harry

> Den 11 okt. 2017 17:01 skrev "Harry Wentland" <harry.wentland at amd.com <mailto:harry.wentland at amd.com>>:
> 
>     This is confusing as-is and really needs a comment.
> 
>     Signed-off-by: Harry Wentland <harry.wentland at amd.com <mailto:harry.wentland at amd.com>>
>     ---
>      drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c | 4 ++++
>      1 file changed, 4 insertions(+)
> 
>     diff --git a/drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c b/drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c
>     index b6abe0f3bb15..f95dc4ff9a23 100644
>     --- a/drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c
>     +++ b/drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.c
>     @@ -27,6 +27,7 @@
> 
>      float dcn_bw_mod(const float arg1, const float arg2)
>      {
>     +       /* NaN checks */
>             if (arg1 != arg1)
>                     return arg2;
>             if (arg2 != arg2)
>     @@ -36,6 +37,7 @@ float dcn_bw_mod(const float arg1, const float arg2)
> 
>      float dcn_bw_min2(const float arg1, const float arg2)
>      {
>     +       /* NaN checks */
>             if (arg1 != arg1)
>                     return arg2;
>             if (arg2 != arg2)
>     @@ -45,6 +47,7 @@ float dcn_bw_min2(const float arg1, const float arg2)
> 
>      unsigned int dcn_bw_max(const unsigned int arg1, const unsigned int arg2)
>      {
>     +       /* NaN checks */
> 
> 
> How can the int arguments be NaN?
> 
> BR
> Nils
> 
>             if (arg1 != arg1)
>                     return arg2;
>             if (arg2 != arg2)
>     @@ -53,6 +56,7 @@ unsigned int dcn_bw_max(const unsigned int arg1, const unsigned int arg2)
>      }
>      float dcn_bw_max2(const float arg1, const float arg2)
>      {
>     +       /* NaN checks */
>             if (arg1 != arg1)
>                     return arg2;
>             if (arg2 != arg2)
>     --
>     2.14.1
> 
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>