According to BSpec max BW per slice is calculated using formula
Max BW = CDCLK * 64. Currently when calculating min CDCLK we
account only per plane requirements, however in order to avoid
FIFO underruns we need to estimate accumulated BW consumed by
all planes(ddb entries basically) residing on that particular
DBuf slice. This will allow us to put CDCLK lower and save power
when we don't need that much bandwidth or gain additional
performance once plane consumption grows.
v2: - Fix long line warning
- Limited new DBuf bw checks to only gens >= 11
v3: - Lets track used Dbuf bw per slice and per crtc in bw state
(or may be in DBuf state in future), that way we don't need
to have all crtcs in state and those only if we detect if
are actually going to change cdclk, just same way as we
do with other stuff, i.e intel_atomic_serialize_global_state
and co. Just as per Ville's paradigm.
- Made dbuf bw calculation procedure look nicer by introducing
for_each_dbuf_slice_in_mask - we often will now need to iterate
slices using mask.
- According to experimental results CDCLK * 64 accounts for
overall bandwidth across all dbufs, not per dbuf.
v4: - Fixed missing const(Ville)
- Removed spurious whitespaces(Ville)
- Fixed local variable init(reduced scope where not needed)
- Added some comments about data rate for planar formats
- Changed struct intel_crtc_bw to intel_dbuf_bw
- Moved dbuf bw calculation to intel_compute_min_cdclk(Ville)
v5: - Removed unneeded macro
v6: - Prevent too frequent CDCLK switching back and forth:
Always switch to higher CDCLK when needed to prevent bandwidth
issues, however don't switch to lower CDCLK earlier than once
in 30 minutes in order to prevent constant modeset blinking.
We could of course not switch back at all, however this is
bad from power consumption point of view.
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_bw.c | 73 +++++++++++++++++++-
drivers/gpu/drm/i915/display/intel_bw.h | 7 ++
drivers/gpu/drm/i915/display/intel_cdclk.c | 54 +++++++++++++++
drivers/gpu/drm/i915/display/intel_cdclk.h | 5 +-
drivers/gpu/drm/i915/display/intel_display.c | 8 +++
drivers/gpu/drm/i915/intel_pm.c | 31 ++++++++-
drivers/gpu/drm/i915/intel_pm.h | 3 +
7 files changed, 177 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
index 6e7cc3a4f1aa..cbfab51d75ee 100644
--- a/drivers/gpu/drm/i915/display/intel_bw.c
+++ b/drivers/gpu/drm/i915/display/intel_bw.c
@@ -6,6 +6,7 @@
#include <drm/drm_atomic_state_helper.h>
#include "intel_bw.h"
+#include "intel_pm.h"
#include "intel_display_types.h"
#include "intel_sideband.h"
@@ -333,7 +334,6 @@ static unsigned int intel_bw_crtc_data_rate(const struct intel_crtc_state *crtc_
return data_rate;
}
-
void intel_bw_crtc_update(struct intel_bw_state *bw_state,
const struct intel_crtc_state *crtc_state)
{
@@ -410,6 +410,77 @@ intel_atomic_get_bw_state(struct intel_atomic_state *state)
return to_intel_bw_state(bw_state);
}
+int intel_bw_calc_min_cdclk(struct intel_atomic_state *state)
+{
+ struct drm_i915_private *dev_priv = to_i915(state->base.dev);
+ int i;
+ const struct intel_crtc_state *crtc_state;
+ struct intel_crtc *crtc;
+ int max_bw = 0;
+ int min_cdclk;
+ struct intel_bw_state *bw_state;
+ int slice_id;
+
+ bw_state = intel_atomic_get_bw_state(state);
+ if (IS_ERR(bw_state))
+ return PTR_ERR(bw_state);
+
+ for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
+ enum plane_id plane_id;
+ struct intel_dbuf_bw *crtc_bw = &bw_state->dbuf_bw[crtc->pipe];
+
+ memset(&crtc_bw->used_bw, 0, sizeof(crtc_bw->used_bw));
+
+ for_each_plane_id_on_crtc(crtc, plane_id) {
+ const struct skl_ddb_entry *plane_alloc =
+ &crtc_state->wm.skl.plane_ddb_y[plane_id];
+ const struct skl_ddb_entry *uv_plane_alloc =
+ &crtc_state->wm.skl.plane_ddb_uv[plane_id];
+ unsigned int data_rate = crtc_state->data_rate[plane_id];
+ unsigned int dbuf_mask = 0;
+
+ dbuf_mask |= skl_ddb_dbuf_slice_mask(dev_priv, plane_alloc);
+ dbuf_mask |= skl_ddb_dbuf_slice_mask(dev_priv, uv_plane_alloc);
+
+ /*
+ * FIXME: To calculate that more properly we probably need to
+ * to split per plane data_rate into data_rate_y and data_rate_uv
+ * for multiplanar formats in order not to get accounted those twice
+ * if they happen to reside on different slices.
+ * However for pre-icl this would work anyway because we have only single
+ * slice and for icl+ uv plane has non-zero data rate.
+ * So in worst case those calculation are a bit pessimistic, which
+ * shouldn't pose any significant problem anyway.
+ */
+ for_each_dbuf_slice_in_mask(slice_id, dbuf_mask)
+ crtc_bw->used_bw[slice_id] += data_rate;
+ }
+ }
+
+ for_each_dbuf_slice(slice_id) {
+ int total_bw_per_slice = 0;
+ enum pipe pipe;
+
+ /*
+ * Current experimental observations show that contrary to BSpec
+ * we get underruns once we exceed 64 * CDCLK for slices in total.
+ * As a temporary measure in order not to keep CDCLK bumped up all the
+ * time we calculate CDCLK according to this formula for overall bw
+ * consumed by slices.
+ */
+ for_each_pipe(dev_priv, pipe) {
+ struct intel_dbuf_bw *crtc_bw = &bw_state->dbuf_bw[pipe];
+
+ total_bw_per_slice += crtc_bw->used_bw[slice_id];
+ }
+ max_bw += total_bw_per_slice;
+ }
+
+ min_cdclk = max_bw / 64;
+
+ return min_cdclk;
+}
+
int intel_bw_atomic_check(struct intel_atomic_state *state)
{
struct drm_i915_private *dev_priv = to_i915(state->base.dev);
diff --git a/drivers/gpu/drm/i915/display/intel_bw.h b/drivers/gpu/drm/i915/display/intel_bw.h
index 898b4a85ccab..b82bb5c9ce7b 100644
--- a/drivers/gpu/drm/i915/display/intel_bw.h
+++ b/drivers/gpu/drm/i915/display/intel_bw.h
@@ -10,13 +10,19 @@
#include "intel_display.h"
#include "intel_global_state.h"
+#include "intel_display_power.h"
struct drm_i915_private;
struct intel_atomic_state;
struct intel_crtc_state;
+struct intel_dbuf_bw {
+ int used_bw[I915_MAX_DBUF_SLICES];
+};
+
struct intel_bw_state {
struct intel_global_state base;
+ struct intel_dbuf_bw dbuf_bw[I915_MAX_PIPES];
/*
* Contains a bit mask, used to determine, whether correspondent
@@ -47,5 +53,6 @@ int intel_bw_init(struct drm_i915_private *dev_priv);
int intel_bw_atomic_check(struct intel_atomic_state *state);
void intel_bw_crtc_update(struct intel_bw_state *bw_state,
const struct intel_crtc_state *crtc_state);
+int intel_bw_calc_min_cdclk(struct intel_atomic_state *state);
#endif /* __INTEL_BW_H__ */
diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 979a0241fdcb..45343b9a9650 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -21,10 +21,12 @@
* DEALINGS IN THE SOFTWARE.
*/
+#include <linux/time.h>
#include "intel_atomic.h"
#include "intel_cdclk.h"
#include "intel_display_types.h"
#include "intel_sideband.h"
+#include "intel_bw.h"
/**
* DOC: CDCLK / RAWCLK
@@ -2090,6 +2092,23 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state)
return min_cdclk;
}
+static int intel_compute_dbuf_min_cdclk(struct intel_atomic_state *state)
+{
+ struct drm_i915_private *dev_priv = to_i915(state->base.dev);
+ int min_cdclk = intel_bw_calc_min_cdclk(state);
+
+ DRM_DEBUG_KMS("DBuf bw min cdclk %d\n", min_cdclk);
+
+ if (min_cdclk > dev_priv->max_cdclk_freq) {
+ drm_dbg_kms(&dev_priv->drm,
+ "required cdclk (%d kHz) exceeds max (%d kHz)\n",
+ min_cdclk, dev_priv->max_cdclk_freq);
+ return -EINVAL;
+ }
+
+ return min_cdclk;
+}
+
static int intel_compute_min_cdclk(struct intel_cdclk_state *cdclk_state)
{
struct intel_atomic_state *state = cdclk_state->base.state;
@@ -2098,6 +2117,17 @@ static int intel_compute_min_cdclk(struct intel_cdclk_state *cdclk_state)
struct intel_crtc_state *crtc_state;
int min_cdclk, i;
enum pipe pipe;
+ int dbuf_bw_min_cdclk = 0;
+ bool cdclk_updated = false;
+ struct timespec64 t;
+
+ ktime_get_coarse_real_ts64(&t);
+
+ if (INTEL_GEN(dev_priv) >= 11) {
+ dbuf_bw_min_cdclk = intel_compute_dbuf_min_cdclk(state);
+ if (dbuf_bw_min_cdclk < 0)
+ return dbuf_bw_min_cdclk;
+ }
for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
int ret;
@@ -2106,16 +2136,40 @@ static int intel_compute_min_cdclk(struct intel_cdclk_state *cdclk_state)
if (min_cdclk < 0)
return min_cdclk;
+ min_cdclk = max(min_cdclk, dbuf_bw_min_cdclk);
+
if (cdclk_state->min_cdclk[i] == min_cdclk)
continue;
+ /*
+ * We always set CDCLK higher if needed to prevent underruns
+ * and running out of bandwidth, however we don't lower it
+ * more often than once in 30 minutes, in order to prevent
+ * too frequent full modeset being done.
+ * Keeping CDCLK high all the time is also bad strategy from
+ * power consumption perspective, so this approach is a compromise.
+ */
+ if (cdclk_state->min_cdclk[i] > min_cdclk) {
+ int current_seconds, last_seconds;
+
+ current_seconds = (int)t.tv_sec;
+ last_seconds = (int)cdclk_state->last_updated.tv_sec;
+
+ if ((current_seconds - last_seconds) < 1800)
+ continue;
+ }
+
cdclk_state->min_cdclk[i] = min_cdclk;
+ cdclk_updated = true;
ret = intel_atomic_lock_global_state(&cdclk_state->base);
if (ret)
return ret;
}
+ if (cdclk_updated)
+ cdclk_state->last_updated = t;
+
min_cdclk = cdclk_state->force_min_cdclk;
for_each_pipe(dev_priv, pipe)
min_cdclk = max(cdclk_state->min_cdclk[pipe], min_cdclk);
diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.h b/drivers/gpu/drm/i915/display/intel_cdclk.h
index 5731806e4cee..6270b10e8eef 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.h
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.h
@@ -7,7 +7,7 @@
#define __INTEL_CDCLK_H__
#include <linux/types.h>
-
+#include <linux/time.h>
#include "i915_drv.h"
#include "intel_display.h"
#include "intel_global_state.h"
@@ -53,6 +53,9 @@ struct intel_cdclk_state {
/* bitmask of active pipes */
u8 active_pipes;
+
+ /* timestamp in seconds when CDCLK was updated last time */
+ struct timespec64 last_updated;
};
int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state);
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 33f566114c81..c24440698672 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -14624,6 +14624,14 @@ static int intel_atomic_check_planes(struct intel_atomic_state *state,
if (old_active_planes == new_active_planes)
continue;
+ /*
+ * active_planes bitmask has been updated, whenever amount
+ * of active planes had changed we need to recalculate CDCLK
+ * as it depends on total bandwidth now, not only min_cdclk
+ * per plane.
+ */
+ *need_cdclk_calc = true;
+
ret = intel_crtc_add_planes_to_state(state, crtc, new_active_planes);
if (ret)
return ret;
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 416cb1a1e7cb..7c0ec0efef11 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3929,10 +3929,9 @@ icl_get_first_dbuf_slice_offset(u32 dbuf_slice_mask,
return offset;
}
-static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv)
+u16 intel_get_ddb_size(struct drm_i915_private *dev_priv)
{
u16 ddb_size = INTEL_INFO(dev_priv)->ddb_size;
-
drm_WARN_ON(&dev_priv->drm, ddb_size == 0);
if (INTEL_GEN(dev_priv) < 11)
@@ -3941,6 +3940,34 @@ static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv)
return ddb_size;
}
+u32 skl_ddb_dbuf_slice_mask(struct drm_i915_private *dev_priv,
+ const struct skl_ddb_entry *entry)
+{
+ u32 slice_mask = 0;
+ u16 ddb_size = intel_get_ddb_size(dev_priv);
+ u16 num_supported_slices = INTEL_INFO(dev_priv)->num_supported_dbuf_slices;
+ u16 slice_size = ddb_size / num_supported_slices;
+ u16 start_slice;
+ u16 end_slice;
+
+ if (!skl_ddb_entry_size(entry))
+ return 0;
+
+ start_slice = entry->start / slice_size;
+ end_slice = (entry->end - 1) / slice_size;
+
+ /*
+ * Per plane DDB entry can in a really worst case be on multiple slices
+ * but single entry is anyway contigious.
+ */
+ while (start_slice <= end_slice) {
+ slice_mask |= BIT(start_slice);
+ start_slice++;
+ }
+
+ return slice_mask;
+}
+
static u8 skl_compute_dbuf_slices(const struct intel_crtc_state *crtc_state,
u8 active_pipes);
diff --git a/drivers/gpu/drm/i915/intel_pm.h b/drivers/gpu/drm/i915/intel_pm.h
index fd1dc422e6c5..de7f6c4103ba 100644
--- a/drivers/gpu/drm/i915/intel_pm.h
+++ b/drivers/gpu/drm/i915/intel_pm.h
@@ -38,6 +38,9 @@ void skl_pipe_ddb_get_hw_state(struct intel_crtc *crtc,
struct skl_ddb_entry *ddb_y,
struct skl_ddb_entry *ddb_uv);
void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv);
+u16 intel_get_ddb_size(struct drm_i915_private *dev_priv);
+u32 skl_ddb_dbuf_slice_mask(struct drm_i915_private *dev_priv,
+ const struct skl_ddb_entry *entry);
void skl_pipe_wm_get_hw_state(struct intel_crtc *crtc,
struct skl_pipe_wm *out);
void g4x_wm_sanitize(struct drm_i915_private *dev_priv);
--
2.24.1.485.gad05a3d8e5
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