Revert "drm/radeon: rework pll selection (v3)"

commit 2f1f4d9b upstream.

This reverts commit 985f61f7.

This commit fixed certain cases, but ended up regressing others
due to limitations in the current KMS API.  A proper fix is too
invasive for 3.6.  Push it back to 3.7.
Reported-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[bwh: Backported to 3.2: drop the DCE6 case]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -1446,98 +1446,14 @@ static void radeon_legacy_atom_fixup(struct drm_crtc *crtc)
 	}
 }
 
-/**
- * radeon_get_pll_use_mask - look up a mask of which pplls are in use
- *
- * @crtc: drm crtc
- *
- * Returns the mask of which PPLLs (Pixel PLLs) are in use.
- */
-static u32 radeon_get_pll_use_mask(struct drm_crtc *crtc)
-{
-	struct drm_device *dev = crtc->dev;
-	struct drm_crtc *test_crtc;
-	struct radeon_crtc *radeon_test_crtc;
-	u32 pll_in_use = 0;
-
-	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
-		if (crtc == test_crtc)
-			continue;
-
-		radeon_test_crtc = to_radeon_crtc(test_crtc);
-		if (radeon_test_crtc->pll_id != ATOM_PPLL_INVALID)
-			pll_in_use |= (1 << radeon_test_crtc->pll_id);
-	}
-	return pll_in_use;
-}
-
-/**
- * radeon_get_shared_dp_ppll - return the PPLL used by another crtc for DP
- *
- * @crtc: drm crtc
- *
- * Returns the PPLL (Pixel PLL) used by another crtc/encoder which is
- * also in DP mode.  For DP, a single PPLL can be used for all DP
- * crtcs/encoders.
- */
-static int radeon_get_shared_dp_ppll(struct drm_crtc *crtc)
-{
-	struct drm_device *dev = crtc->dev;
-	struct drm_encoder *test_encoder;
-	struct radeon_crtc *radeon_test_crtc;
-
-	list_for_each_entry(test_encoder, &dev->mode_config.encoder_list, head) {
-		if (test_encoder->crtc && (test_encoder->crtc != crtc)) {
-			if (ENCODER_MODE_IS_DP(atombios_get_encoder_mode(test_encoder))) {
-				/* for DP use the same PLL for all */
-				radeon_test_crtc = to_radeon_crtc(test_encoder->crtc);
-				if (radeon_test_crtc->pll_id != ATOM_PPLL_INVALID)
-					return radeon_test_crtc->pll_id;
-			}
-		}
-	}
-	return ATOM_PPLL_INVALID;
-}
-
-/**
- * radeon_atom_pick_pll - Allocate a PPLL for use by the crtc.
- *
- * @crtc: drm crtc
- *
- * Returns the PPLL (Pixel PLL) to be used by the crtc.  For DP monitors
- * a single PPLL can be used for all DP crtcs/encoders.  For non-DP
- * monitors a dedicated PPLL must be used.  If a particular board has
- * an external DP PLL, return ATOM_PPLL_INVALID to skip PLL programming
- * as there is no need to program the PLL itself.  If we are not able to
- * allocate a PLL, return ATOM_PPLL_INVALID to skip PLL programming to
- * avoid messing up an existing monitor.
- *
- * Asic specific PLL information
- *
- * DCE 6.1
- * - PPLL2 is only available to UNIPHYA (both DP and non-DP)
- * - PPLL0, PPLL1 are available for UNIPHYB/C/D/E/F (both DP and non-DP)
- *
- * DCE 6.0
- * - PPLL0 is available to all UNIPHY (DP only)
- * - PPLL1, PPLL2 are available for all UNIPHY (both DP and non-DP) and DAC
- *
- * DCE 5.0
- * - DCPLL is available to all UNIPHY (DP only)
- * - PPLL1, PPLL2 are available for all UNIPHY (both DP and non-DP) and DAC
- *
- * DCE 3.0/4.0/4.1
- * - PPLL1, PPLL2 are available for all UNIPHY (both DP and non-DP) and DAC
- *
- */
 static int radeon_atom_pick_pll(struct drm_crtc *crtc)
 {
 	struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
 	struct drm_device *dev = crtc->dev;
 	struct radeon_device *rdev = dev->dev_private;
 	struct drm_encoder *test_encoder;
-	u32 pll_in_use;
-	int pll;
+	struct drm_crtc *test_crtc;
+	uint32_t pll_in_use = 0;
 
 	if (ASIC_IS_DCE4(rdev)) {
 		list_for_each_entry(test_encoder, &dev->mode_config.encoder_list, head) {
@@ -1545,7 +1461,7 @@ static int radeon_atom_pick_pll(struct drm_crtc *crtc)
 				/* in DP mode, the DP ref clock can come from PPLL, DCPLL, or ext clock,
 				 * depending on the asic:
 				 * DCE4: PPLL or ext clock
-				 * DCE5: PPLL, DCPLL, or ext clock
+				 * DCE5: DCPLL or ext clock
 				 *
 				 * Setting ATOM_PPLL_INVALID will cause SetPixelClock to skip
 				 * PPLL/DCPLL programming and only program the DP DTO for the
@@ -1553,31 +1469,29 @@ static int radeon_atom_pick_pll(struct drm_crtc *crtc)
 				 */
 				if (ENCODER_MODE_IS_DP(atombios_get_encoder_mode(test_encoder))) {
 					if (rdev->clock.dp_extclk)
-						/* skip PPLL programming if using ext clock */
 						return ATOM_PPLL_INVALID;
 					else if (ASIC_IS_DCE5(rdev))
-						/* use DCPLL for all DP */
 						return ATOM_DCPLL;
-					else {
-						/* use the same PPLL for all DP monitors */
-						pll = radeon_get_shared_dp_ppll(crtc);
-						if (pll != ATOM_PPLL_INVALID)
-							return pll;
-					}
 				}
-				break;
 			}
 		}
-		/* all other cases */
-		pll_in_use = radeon_get_pll_use_mask(crtc);
-		if (!(pll_in_use & (1 << ATOM_PPLL2)))
-			return ATOM_PPLL2;
-		if (!(pll_in_use & (1 << ATOM_PPLL1)))
+
+		/* otherwise, pick one of the plls */
+		list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
+			struct radeon_crtc *radeon_test_crtc;
+
+			if (crtc == test_crtc)
+				continue;
+
+			radeon_test_crtc = to_radeon_crtc(test_crtc);
+			if ((radeon_test_crtc->pll_id >= ATOM_PPLL1) &&
+			    (radeon_test_crtc->pll_id <= ATOM_PPLL2))
+				pll_in_use |= (1 << radeon_test_crtc->pll_id);
+		}
+		if (!(pll_in_use & 1))
 			return ATOM_PPLL1;
-		DRM_ERROR("unable to allocate a PPLL\n");
-		return ATOM_PPLL_INVALID;
+		return ATOM_PPLL2;
 	} else
-		/* use PPLL1 or PPLL2 */
 		return radeon_crtc->crtc_id;
 
 }
@@ -1696,7 +1610,7 @@ static void atombios_crtc_disable(struct drm_crtc *crtc)
 		break;
 	}
 done:
-	radeon_crtc->pll_id = ATOM_PPLL_INVALID;
+	radeon_crtc->pll_id = -1;
 }
 
 static const struct drm_crtc_helper_funcs atombios_helper_funcs = {
@@ -1745,6 +1659,6 @@ void radeon_atombios_init_crtc(struct drm_device *dev,
 		else
 			radeon_crtc->crtc_offset = 0;
 	}
-	radeon_crtc->pll_id = ATOM_PPLL_INVALID;
+	radeon_crtc->pll_id = -1;
 	drm_crtc_helper_add(&radeon_crtc->base, &atombios_helper_funcs);
 }