[Intel-gfx] [PATCH v2] drm/i915/skl: Skip remaining dividers when deviation is 0

[Damien Lespiau]

We can't improve a 0 deviation, so when we find such a divider, skip the
remaining ones they won't be better.

This short-circuit the search for 34 of the 373 test frequencies in the
corresponding i-g-t test (tools/skl_compute_wrpll)

v2: Place the short-circuiting code in skl_compute_wrpll() (Paulo)

(I'm sure nobody will notice the spurious removal of a blank line)

Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
Suggested-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/intel_ddi.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index f6b3ccc..42c1487 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1149,7 +1149,6 @@ static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx,
 		ctx->dco_freq = dco_freq;
 		ctx->p = divider;
 	}
-
 }
 
 static void skl_wrpll_get_multipliers(unsigned int p,
@@ -1315,9 +1314,17 @@ skl_ddi_calculate_wrpll(int clock /* in Hz */,
 						      dco_central_freq[dco],
 						      dco_freq,
 						      p);
+				/*
+				 * Skip the remaining dividers if we're sure to
+				 * have found the definitive divider, we can't
+				 * improve a 0 deviation.
+				 */
+				if (ctx.min_deviation == 0)
+					goto skip_remaining_dividers;
 			}
 		}
 
+skip_remaining_dividers:
 		/*
 		 * If a solution is found with an even divider, prefer
 		 * this one.
-- 
2.1.0