Added proper DBuf slice mapping to correspondent
pipes, depending on pipe configuration as stated
in BSpec.

v2:
    - Remove unneeded braces
    - Stop using macro for DBuf assignments as
      it seems to reduce readability.

v3: Start using enabled slices mask in dev_priv

v4: Renamed "enabled_slices" used in dev_priv
    to "enabled_dbuf_slices_mask"(Matt Roper)

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 226 ++++++++++++++++++++++++++++++--
 1 file changed, 216 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 111bcafd6e4c..a13052b2c2ef 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3832,13 +3832,30 @@ bool intel_can_enable_sagv(struct intel_atomic_state 
*state)
        return true;
 }
 
+/*
+ * Calculate initial DBuf slice offset, based on slice size
+ * and mask(i.e if slice size is 1024 and second slice is enabled
+ * offset would be 1024)
+ */
+static u32 icl_get_first_dbuf_slice_offset(u32 dbuf_slice_mask,
+                                          u32 slice_size, u32 ddb_size)
+{
+       u32 offset = 0;
+
+       if (!dbuf_slice_mask)
+               return 0;
+
+       offset = (ffs(dbuf_slice_mask) - 1) * slice_size;
+
+       WARN_ON(offset >= ddb_size);
+       return offset;
+}
+
 static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv,
                              const struct intel_crtc_state *crtc_state,
                              const u64 total_data_rate,
                              const int num_active)
 {
-       struct drm_atomic_state *state = crtc_state->uapi.state;
-       struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
        u16 ddb_size = INTEL_INFO(dev_priv)->ddb_size;
 
        WARN_ON(ddb_size == 0);
@@ -3846,12 +3863,13 @@ static u16 intel_get_ddb_size(struct drm_i915_private 
*dev_priv,
        if (INTEL_GEN(dev_priv) < 11)
                return ddb_size - 4; /* 4 blocks for bypass path allocation */
 
-       intel_state->enabled_dbuf_slices_mask = DBUF_S1_BIT;
-       ddb_size /= 2;
-
        return ddb_size;
 }
 
+u32 i915_possible_dbuf_slices(struct drm_i915_private *dev_priv,
+                             int pipe, u32 active_pipes,
+                             const struct intel_crtc_state *crtc_state);
+
 static void
 skl_ddb_get_pipe_allocation_limits(struct drm_i915_private *dev_priv,
                                   const struct intel_crtc_state *crtc_state,
@@ -3866,7 +3884,14 @@ skl_ddb_get_pipe_allocation_limits(struct 
drm_i915_private *dev_priv,
        u32 pipe_width = 0, total_width = 0, width_before_pipe = 0;
        enum pipe for_pipe = to_intel_crtc(for_crtc)->pipe;
        u16 ddb_size;
+       u32 ddb_range_size;
        u32 i;
+       u32 dbuf_slice_mask;
+       u32 active_pipes;
+       u32 offset;
+       u32 slice_size;
+       u32 total_slice_mask;
+       u32 start, end;
 
        if (WARN_ON(!state) || !crtc_state->hw.active) {
                alloc->start = 0;
@@ -3875,14 +3900,19 @@ skl_ddb_get_pipe_allocation_limits(struct 
drm_i915_private *dev_priv,
                return;
        }
 
-       if (intel_state->active_pipe_changes)
+       if (intel_state->active_pipe_changes) {
                *num_active = hweight8(intel_state->active_pipes);
-       else
+               active_pipes = intel_state->active_pipes;
+       } else {
                *num_active = hweight8(dev_priv->active_pipes);
+               active_pipes = dev_priv->active_pipes;
+       }
 
        ddb_size = intel_get_ddb_size(dev_priv, crtc_state, total_data_rate,
                                      *num_active);
 
+       slice_size = ddb_size / INTEL_INFO(dev_priv)->num_supported_dbuf_slices;
+
        /*
         * If the state doesn't change the active CRTC's or there is no
         * modeset request, then there's no need to recalculate;
@@ -3900,18 +3930,68 @@ skl_ddb_get_pipe_allocation_limits(struct 
drm_i915_private *dev_priv,
                return;
        }
 
+       /*
+        * Get allowed DBuf slices for correspondent pipe and platform.
+        */
+       dbuf_slice_mask = i915_possible_dbuf_slices(dev_priv, for_pipe,
+                                                   active_pipes, crtc_state);
+
+       DRM_DEBUG_KMS("DBuf slice mask %x pipe %d active pipes %x\n",
+                     dbuf_slice_mask,
+                     for_pipe, active_pipes);
+
+       /*
+        * Figure out at which DBuf slice we start, i.e if we start at Dbuf S2
+        * and slice size is 1024, the offset would be 1024
+        */
+       offset = icl_get_first_dbuf_slice_offset(dbuf_slice_mask,
+                                                slice_size, ddb_size);
+
+       /*
+        * Figure out total size of allowed DBuf slices, which is basically
+        * a number of allowed slices for that pipe multiplied by slice size.
+        * Inside of this
+        * range ddb entries are still allocated in proportion to display width.
+        */
+       ddb_range_size = hweight8(dbuf_slice_mask) * slice_size;
+
        /*
         * Watermark/ddb requirement highly depends upon width of the
         * framebuffer, So instead of allocating DDB equally among pipes
         * distribute DDB based on resolution/width of the display.
         */
+       total_slice_mask = dbuf_slice_mask;
        for_each_new_intel_crtc_in_state(intel_state, crtc, crtc_state, i) {
                const struct drm_display_mode *adjusted_mode =
                        &crtc_state->hw.adjusted_mode;
                enum pipe pipe = crtc->pipe;
                int hdisplay, vdisplay;
+               u32 pipe_dbuf_slice_mask =
+                                       i915_possible_dbuf_slices(dev_priv,
+                                                                 pipe,
+                                                                 active_pipes,
+                                                                 crtc_state);
+
+               if (!crtc_state->hw.active)
+                       continue;
+
+               /*
+                * According to BSpec pipe can share one dbuf slice with another
+                * pipes or pipe can use multiple dbufs, in both cases we
+                * account for other pipes only if they have exactly same mask.
+                * However we need to account how many slices we should enable
+                * in total.
+                */
+               total_slice_mask |= pipe_dbuf_slice_mask;
 
-               if (!crtc_state->hw.enable)
+               /*
+                * Do not account pipes using other slice sets
+                * luckily as of current BSpec slice sets do not partially
+                * intersect(pipes share either same one slice or same slice set
+                * i.e no partial intersection), so it is enough to check for
+                * equality for now.
+                */
+               if (dbuf_slice_mask != pipe_dbuf_slice_mask)
                        continue;
 
                drm_mode_get_hv_timing(adjusted_mode, &hdisplay, &vdisplay);
@@ -3923,8 +4003,19 @@ skl_ddb_get_pipe_allocation_limits(struct 
drm_i915_private *dev_priv,
                        pipe_width = hdisplay;
        }
 
-       alloc->start = ddb_size * width_before_pipe / total_width;
-       alloc->end = ddb_size * (width_before_pipe + pipe_width) / total_width;
+       intel_state->enabled_dbuf_slices_mask = total_slice_mask;
+
+       start = ddb_range_size * width_before_pipe / total_width;
+       end = ddb_range_size * (width_before_pipe + pipe_width) / total_width;
+
+       alloc->start = offset + start;
+       alloc->end = offset + end;
+
+       DRM_DEBUG_KMS("Pipe %d ddb %d-%d\n", for_pipe,
+                     alloc->start, alloc->end);
+       DRM_DEBUG_KMS("Enabled ddb slices mask %x num supported %d\n",
+                     intel_state->enabled_dbuf_slices_mask,
+                     INTEL_INFO(dev_priv)->num_supported_dbuf_slices);
 }
 
 static int skl_compute_wm_params(const struct intel_crtc_state *crtc_state,
@@ -4094,6 +4185,121 @@ skl_plane_downscale_amount(const struct 
intel_crtc_state *crtc_state,
        return mul_fixed16(downscale_w, downscale_h);
 }
 
+struct dbuf_slice_conf_entry {
+       u32 active_pipes;
+       u32 dbuf_mask[I915_MAX_PIPES];
+};
+
+/*
+ * Table taken from Bspec 12716
+ * Pipes do have some preferred DBuf slice affinity,
+ * plus there are some hardcoded requirements on how
+ * those should be distributed for multipipe scenarios.
+ * For more DBuf slices algorithm can get even more messy
+ * and less readable, so decided to use a table almost
+ * as is from BSpec itself - that way it is at least easier
+ * to compare, change and check.
+ */
+static struct dbuf_slice_conf_entry icl_allowed_dbufs[] = {
+       { BIT(PIPE_A), { DBUF_S1_BIT, 0, 0, 0 } },
+       { BIT(PIPE_B), { 0, DBUF_S1_BIT, 0, 0 } },
+       { BIT(PIPE_C), { 0, 0, DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_A) | BIT(PIPE_B), { DBUF_S1_BIT, DBUF_S2_BIT, 0, 0 } },
+       { BIT(PIPE_A) | BIT(PIPE_C), { DBUF_S1_BIT, 0, DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_B) | BIT(PIPE_C), { 0, DBUF_S1_BIT, DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_A) | BIT(PIPE_B) | BIT(PIPE_C),
+               { DBUF_S1_BIT, DBUF_S1_BIT, DBUF_S2_BIT, 0 } }
+};
+
+/*
+ * Table taken from Bspec 49255
+ * Pipes do have some preferred DBuf slice affinity,
+ * plus there are some hardcoded requirements on how
+ * those should be distributed for multipipe scenarios.
+ * For more DBuf slices algorithm can get even more messy
+ * and less readable, so decided to use a table almost
+ * as is from BSpec itself - that way it is at least easier
+ * to compare, change and check.
+ */
+static struct dbuf_slice_conf_entry tgl_allowed_dbufs[] = {
+       { BIT(PIPE_A), { DBUF_S1_BIT | DBUF_S2_BIT, 0, 0, 0 } },
+       { BIT(PIPE_B), { 0, DBUF_S1_BIT | DBUF_S2_BIT, 0, 0 } },
+       { BIT(PIPE_C), { 0, 0, DBUF_S1_BIT | DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_D), { 0, 0, 0, DBUF_S1_BIT | DBUF_S2_BIT } },
+       { BIT(PIPE_A) | BIT(PIPE_B), { DBUF_S2_BIT, DBUF_S1_BIT, 0, 0 } },
+       { BIT(PIPE_A) | BIT(PIPE_C), { DBUF_S1_BIT, 0, DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_A) | BIT(PIPE_D), { DBUF_S1_BIT, 0, 0, DBUF_S2_BIT } },
+       { BIT(PIPE_B) | BIT(PIPE_C), { 0, DBUF_S1_BIT, DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_B) | BIT(PIPE_D), { 0, DBUF_S1_BIT, 0, DBUF_S2_BIT } },
+       { BIT(PIPE_C) | BIT(PIPE_D), { 0, 0, DBUF_S2_BIT, DBUF_S2_BIT } },
+       { BIT(PIPE_A) | BIT(PIPE_B) | BIT(PIPE_C),
+               { DBUF_S1_BIT, DBUF_S1_BIT, DBUF_S2_BIT, 0 } },
+       { BIT(PIPE_A) | BIT(PIPE_B) | BIT(PIPE_D),
+               { DBUF_S1_BIT, DBUF_S1_BIT, 0, DBUF_S2_BIT } },
+       { BIT(PIPE_A) | BIT(PIPE_C) | BIT(PIPE_D),
+               { DBUF_S1_BIT, 0, DBUF_S2_BIT, DBUF_S2_BIT } },
+       { BIT(PIPE_B) | BIT(PIPE_C) | BIT(PIPE_D),
+               { 0, DBUF_S1_BIT, DBUF_S2_BIT, DBUF_S2_BIT } },
+       { BIT(PIPE_A) | BIT(PIPE_B) | BIT(PIPE_C) | BIT(PIPE_D),
+               { DBUF_S1_BIT, DBUF_S1_BIT, DBUF_S2_BIT, DBUF_S2_BIT } },
+};
+
+static u32 i915_find_pipe_conf(int pipe,
+                              u32 active_pipes,
+                              const struct dbuf_slice_conf_entry *dbuf_slices,
+                              int size)
+{
+       int i;
+
+       for (i = 0; i < size; i++) {
+               if (dbuf_slices[i].active_pipes == active_pipes)
+                       return dbuf_slices[i].dbuf_mask[pipe];
+       }
+       return 0;
+}
+
+/*
+ * This function finds an entry with same enabled pipe configuration and
+ * returns correspondent DBuf slice mask as stated in BSpec for particular
+ * platform.
+ */
+static u32 icl_possible_dbuf_slices(int pipe,
+                                   u32 active_pipes,
+                                   const struct intel_crtc_state *crtc_state)
+{
+       return i915_find_pipe_conf(pipe, active_pipes,
+                                  icl_allowed_dbufs,
+                                  ARRAY_SIZE(icl_allowed_dbufs));
+}
+
+static u32 tgl_possible_dbuf_slices(int pipe,
+                                   u32 active_pipes,
+                                   const struct intel_crtc_state *crtc_state)
+{
+       return i915_find_pipe_conf(pipe, active_pipes,
+                                  tgl_allowed_dbufs,
+                                  ARRAY_SIZE(tgl_allowed_dbufs));
+}
+
+u32 i915_possible_dbuf_slices(struct drm_i915_private *dev_priv,
+                             int pipe, u32 active_pipes,
+                             const struct intel_crtc_state *crtc_state)
+{
+       if (IS_GEN(dev_priv, 11))
+               return icl_possible_dbuf_slices(pipe,
+                                               active_pipes,
+                                               crtc_state);
+       else if (IS_GEN(dev_priv, 12))
+               return tgl_possible_dbuf_slices(pipe,
+                                               active_pipes,
+                                               crtc_state);
+       /*
+        * For anything else just return one slice yet.
+        * Should be extended for other platforms.
+        */
+       return DBUF_S1_BIT;
+}
+
 static u64
 skl_plane_relative_data_rate(const struct intel_crtc_state *crtc_state,
                             const struct intel_plane_state *plane_state,
-- 
2.17.1

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