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drm/i915: Rewrite ABS_DIFF() in a safer manner

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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>
This commit is contained in:
Damien Lespiau 2014-09-04 12:27:23 +01:00 committed by Daniel Vetter
parent 951468f331
commit 2789339044
1 changed files with 9 additions and 5 deletions
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14
drivers/gpu/drm/i915/intel_ddi.c
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@ -424,7 +424,7 @@ intel_ddi_get_crtc_encoder(struct drm_crtc *crtc)
}
#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 @@ intel_ddi_get_crtc_encoder(struct drm_crtc *crtc)
#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 @@ static void wrpll_update_rnp(uint64_t freq2k, unsigned budget,
*/
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;