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Commit 27893390 authored by Damien Lespiau's avatar Damien Lespiau Committed by Daniel Vetter
Browse files

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: default avatarDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 951468f3

drivers/gpu/drm/i915/intel_ddi.c

+9 −5
Original line number Diff line number Diff line
@@ -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;