[Intel-gfx] [PATCH 4/4] drm/i915: reorganize the get_cdclk assignment

[Paulo Zanoni]

Possible problems of the current if-ladder:
  - It's a huge if ladder with almost a different check for each of
    our platforms.
  - It mixes 3 different types of checks: IS_GENX, IS_PLATFORM and
    IS_GROUP_OF_PLATFORMS.
  - As demonstrated by the recent IS_G4X commit, it's not easy to be
    sure if a platform down on the list isn't also checked earlier.
  - As demonstrated by the WARN at the end, it's not easy to be sure
    if we're actually checking for every single platform.

Possible advantages of the new switch statement:
  - It may be easier for the compiler to optimize stuff (I didn't
    check this), especially since the values are labels of an enum.
  - The compiler will tell us in case we miss some platform.
  - All platforms are explicitly there instead of maybe hidden in some
    check for a certain group of platforms such as IS_GEN9_BC.

Possible disadvantages with the new code:
  - A few lines bigger.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/intel_cdclk.c | 103 ++++++++++++++++++++++---------------
 1 file changed, 62 insertions(+), 41 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
index 7c92dc7..58a2f5c 100644
--- a/drivers/gpu/drm/i915/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/intel_cdclk.c
@@ -1789,49 +1789,70 @@ void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
 		dev_priv->display.modeset_calc_cdclk = skl_modeset_calc_cdclk;
 	}
 
-	if (IS_GEN9_BC(dev_priv))
-		dev_priv->display.get_cdclk = skl_get_cdclk;
-	else if (IS_GEN9_LP(dev_priv))
-		dev_priv->display.get_cdclk = bxt_get_cdclk;
-	else if (IS_BROADWELL(dev_priv))
-		dev_priv->display.get_cdclk = bdw_get_cdclk;
-	else if (IS_HASWELL(dev_priv))
-		dev_priv->display.get_cdclk = hsw_get_cdclk;
-	else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
-		dev_priv->display.get_cdclk = vlv_get_cdclk;
-	else if (IS_GEN6(dev_priv) || IS_IVYBRIDGE(dev_priv))
+	switch (INTEL_INFO(dev_priv)->platform) {
+	case INTEL_PLATFORM_UNINITIALIZED:
+		MISSING_CASE(INTEL_INFO(dev_priv)->platform);
+		/* Fall through. */
+	case INTEL_I830:
+		dev_priv->display.get_cdclk = fixed_133mhz_get_cdclk;
+		break;
+	case INTEL_I845G:
+		dev_priv->display.get_cdclk = fixed_200mhz_get_cdclk;
+		break;
+	case INTEL_I85X:
+		dev_priv->display.get_cdclk = i85x_get_cdclk;
+		break;
+	case INTEL_I865G:
+		dev_priv->display.get_cdclk = fixed_266mhz_get_cdclk;
+		break;
+	case INTEL_I915G:
+		dev_priv->display.get_cdclk = fixed_333mhz_get_cdclk;
+		break;
+	case INTEL_I915GM:
+		dev_priv->display.get_cdclk = i915gm_get_cdclk;
+		break;
+	case INTEL_I945G:
+	case INTEL_I965G:
+	case INTEL_SANDYBRIDGE:
+	case INTEL_IVYBRIDGE:
 		dev_priv->display.get_cdclk = fixed_400mhz_get_cdclk;
-	else if (IS_GEN5(dev_priv))
-		dev_priv->display.get_cdclk = fixed_450mhz_get_cdclk;
-	else if (IS_GM45(dev_priv))
-		dev_priv->display.get_cdclk = gm45_get_cdclk;
-	else if (IS_G45(dev_priv))
+		break;
+	case INTEL_I945GM:
+		dev_priv->display.get_cdclk = i945gm_get_cdclk;
+		break;
+	case INTEL_G33:
+	case INTEL_G45:
 		dev_priv->display.get_cdclk = g33_get_cdclk;
-	else if (IS_I965GM(dev_priv))
-		dev_priv->display.get_cdclk = i965gm_get_cdclk;
-	else if (IS_I965G(dev_priv))
-		dev_priv->display.get_cdclk = fixed_400mhz_get_cdclk;
-	else if (IS_PINEVIEW(dev_priv))
+		break;
+	case INTEL_PINEVIEW:
 		dev_priv->display.get_cdclk = pnv_get_cdclk;
-	else if (IS_G33(dev_priv))
-		dev_priv->display.get_cdclk = g33_get_cdclk;
-	else if (IS_I945GM(dev_priv))
-		dev_priv->display.get_cdclk = i945gm_get_cdclk;
-	else if (IS_I945G(dev_priv))
-		dev_priv->display.get_cdclk = fixed_400mhz_get_cdclk;
-	else if (IS_I915GM(dev_priv))
-		dev_priv->display.get_cdclk = i915gm_get_cdclk;
-	else if (IS_I915G(dev_priv))
-		dev_priv->display.get_cdclk = fixed_333mhz_get_cdclk;
-	else if (IS_I865G(dev_priv))
-		dev_priv->display.get_cdclk = fixed_266mhz_get_cdclk;
-	else if (IS_I85X(dev_priv))
-		dev_priv->display.get_cdclk = i85x_get_cdclk;
-	else if (IS_I845G(dev_priv))
-		dev_priv->display.get_cdclk = fixed_200mhz_get_cdclk;
-	else { /* 830 */
-		WARN(!IS_I830(dev_priv),
-		     "Unknown platform. Assuming 133 MHz CDCLK\n");
-		dev_priv->display.get_cdclk = fixed_133mhz_get_cdclk;
+		break;
+	case INTEL_I965GM:
+		dev_priv->display.get_cdclk = i965gm_get_cdclk;
+		break;
+	case INTEL_GM45:
+		dev_priv->display.get_cdclk = gm45_get_cdclk;
+		break;
+	case INTEL_IRONLAKE:
+		dev_priv->display.get_cdclk = fixed_450mhz_get_cdclk;
+		break;
+	case INTEL_VALLEYVIEW:
+	case INTEL_CHERRYVIEW:
+		dev_priv->display.get_cdclk = vlv_get_cdclk;
+		break;
+	case INTEL_HASWELL:
+		dev_priv->display.get_cdclk = hsw_get_cdclk;
+		break;
+	case INTEL_BROADWELL:
+		dev_priv->display.get_cdclk = bdw_get_cdclk;
+		break;
+	case INTEL_SKYLAKE:
+	case INTEL_KABYLAKE:
+		dev_priv->display.get_cdclk = skl_get_cdclk;
+		break;
+	case INTEL_BROXTON:
+	case INTEL_GEMINILAKE:
+		dev_priv->display.get_cdclk = bxt_get_cdclk;
+		break;
 	}
 }
-- 
2.7.4