drm/radeon: rework pll selection (v4)

For DP we can use the same PPLL for all active DP
encoders.  Take advantage of that to prevent cases
where we may end up sharing a PPLL between DP and
non-DP which won't work.  Also clean up the code
a bit.

v2: - fix missing pll_id assignment in crtc init
v3: - fix DP PPLL check
    - document functions
    - break in main encoder search loop after matching.
      no need to keep checking additional encoders.
v4: - same as v3, but re-apply to drm-next as the corner
      cases are fixed properly in subsequent patches.

fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=54471

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 129 insertions, 34 deletions

diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index cc1b2444a5e5..8e73d53b769e 100644
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -1482,14 +1482,98 @@ 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;
-        struct drm_crtc *test_crtc;
-        uint32_t pll_in_use = 0;
+        u32 pll_in_use;
+        int pll;
 
         if (ASIC_IS_DCE61(rdev)) {
                 list_for_each_entry(test_encoder, &dev->mode_config.encoder_list, head) {
@@ -1501,32 +1585,40 @@ static int radeon_atom_pick_pll(struct drm_crtc *crtc)
 
                                 if ((test_radeon_encoder->encoder_id ==
                                      ENCODER_OBJECT_ID_INTERNAL_UNIPHY) &&
-                                    (dig->linkb == false)) /* UNIPHY A uses PPLL2 */
+                                    (dig->linkb == false))
+                                        /* UNIPHY A uses PPLL2 */
                                         return ATOM_PPLL2;
+                                else if (ENCODER_MODE_IS_DP(atombios_get_encoder_mode(test_encoder))) {
+                                        /* UNIPHY B/C/D/E/F */
+                                        if (rdev->clock.dp_extclk)
+                                                /* skip PPLL programming if using ext clock */
+                                                return ATOM_PPLL_INVALID;
+                                        else {
+                                                /* use the same PPLL for all DP monitors */
+                                                pll = radeon_get_shared_dp_ppll(crtc);
+                                                if (pll != ATOM_PPLL_INVALID)
+                                                        return pll;
+                                        }
+                                }
+                                break;
                         }
                 }
                 /* UNIPHY B/C/D/E/F */
-                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_PPLL0) ||
-                            (radeon_test_crtc->pll_id == ATOM_PPLL1))
-                                pll_in_use |= (1 << radeon_test_crtc->pll_id);
-                }
-                if (!(pll_in_use & 4))
+                pll_in_use = radeon_get_pll_use_mask(crtc);
+                if (!(pll_in_use & (1 << ATOM_PPLL0)))
                         return ATOM_PPLL0;
-                return ATOM_PPLL1;
+                if (!(pll_in_use & (1 << ATOM_PPLL1)))
+                        return ATOM_PPLL1;
+                DRM_ERROR("unable to allocate a PPLL\n");
+                return ATOM_PPLL_INVALID;
         } else if (ASIC_IS_DCE4(rdev)) {
                 list_for_each_entry(test_encoder, &dev->mode_config.encoder_list, head) {
                         if (test_encoder->crtc && (test_encoder->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: DCPLL or ext clock
+                                 * DCE5: PPLL, DCPLL, or ext clock
+                                 * DCE6: PPLL, PPLL0, or ext clock
                                  *
                                  * Setting ATOM_PPLL_INVALID will cause SetPixelClock to skip
                                  * PPLL/DCPLL programming and only program the DP DTO for the
@@ -1534,31 +1626,34 @@ 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_DCE6(rdev))
+                                                /* use PPLL0 for all DP */
                                                 return ATOM_PPLL0;
                                         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;
                         }
                 }
-
-                /* 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))
+                /* 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)))
                         return ATOM_PPLL1;
-                return ATOM_PPLL2;
+                DRM_ERROR("unable to allocate a PPLL\n");
+                return ATOM_PPLL_INVALID;
         } else
+                /* use PPLL1 or PPLL2 */
                 return radeon_crtc->crtc_id;
 
 }
@@ -1700,7 +1795,7 @@ static void atombios_crtc_disable(struct drm_crtc *crtc)
                 break;
         }
 done:
-        radeon_crtc->pll_id = -1;
+        radeon_crtc->pll_id = ATOM_PPLL_INVALID;
 }
 
 static const struct drm_crtc_helper_funcs atombios_helper_funcs = {
@@ -1749,6 +1844,6 @@ void radeon_atombios_init_crtc(struct drm_device *dev,
                 else
                         radeon_crtc->crtc_offset = 0;
         }
-        radeon_crtc->pll_id = -1;
+        radeon_crtc->pll_id = ATOM_PPLL_INVALID;
         drm_crtc_helper_add(&radeon_crtc->base, &atombios_helper_funcs);
 }