drm/i915: Rewrite ABS_DIFF() in a safer manner
The new version of the macro does a few things better:
- protect the arguments,
- only evaluate the arguments once,
- check that the arguments are of the same type,
Change LC_FREQ_2K to be a unsigned 64bit constant and removed the '()'
from the caller as a result.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index eed9a2a..b63d4fa 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -424,7 +424,7 @@
}
#define LC_FREQ 2700
-#define LC_FREQ_2K (LC_FREQ * 2000)
+#define LC_FREQ_2K U64_C(LC_FREQ * 2000)
#define P_MIN 2
#define P_MAX 64
@@ -436,7 +436,11 @@
#define VCO_MIN 2400
#define VCO_MAX 4800
-#define ABS_DIFF(a, b) ((a > b) ? (a - b) : (b - a))
+#define abs_diff(a, b) ({ \
+ typeof(a) __a = (a); \
+ typeof(b) __b = (b); \
+ (void) (&__a == &__b); \
+ __a > __b ? (__a - __b) : (__b - __a); })
struct wrpll_rnp {
unsigned p, n2, r2;
@@ -546,9 +550,9 @@
*/
a = freq2k * budget * p * r2;
b = freq2k * budget * best->p * best->r2;
- diff = ABS_DIFF((freq2k * p * r2), (LC_FREQ_2K * n2));
- diff_best = ABS_DIFF((freq2k * best->p * best->r2),
- (LC_FREQ_2K * best->n2));
+ diff = abs_diff(freq2k * p * r2, LC_FREQ_2K * n2);
+ diff_best = abs_diff(freq2k * best->p * best->r2,
+ LC_FREQ_2K * best->n2);
c = 1000000 * diff;
d = 1000000 * diff_best;