[PATCH v3 05/12] drm/i915: Try to program PKG_C_LATENCY more correctly
Ville Syrjala
ville.syrjala at linux.intel.com
Tue Jun 3 14:08:29 UTC 2025
From: Ville Syrjälä <ville.syrjala at linux.intel.com>
The current PKG_C_LATENCY stuff looks busted in several ways:
- doesn't account for multiple pipes from different commits
correctly
- WM_LINETIME is in units of 0.125usec, PKG_C_LATENCY wants
units on 1 usec
- Wa_22020432604 only done when WM1+ are no available for
some reason
- weird VRR state stuff being checked
- use of pointless RMW
Fix it all up. Note that it's still a bit unclear how all this
works, especially how the added_wake_time ties into the flipq
triggers in DMC, and how we need to sequence updates to
PKG_C_LATENCY when enabling/disabling pipes/etc. We may also
need to think what to about the WM1+ disabling and the related
PSR chicken bits when we can use PKG_C_LATENCY for early wake...
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
drivers/gpu/drm/i915/display/intel_display.c | 1 +
.../gpu/drm/i915/display/intel_display_core.h | 6 ++
drivers/gpu/drm/i915/display/skl_watermark.c | 97 +++++++++++--------
3 files changed, 61 insertions(+), 43 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 06f58c062b29..cc8402eaeda3 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7384,6 +7384,7 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
/* Now enable the clocks, plane, pipe, and connectors that we set up. */
display->funcs.display->commit_modeset_enables(state);
+ /* FIXME probably need to sequence this properly */
intel_program_dpkgc_latency(state);
intel_wait_for_vblank_workers(state);
diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
index 5f5dd2722d99..672c18bb2fd6 100644
--- a/drivers/gpu/drm/i915/display/intel_display_core.h
+++ b/drivers/gpu/drm/i915/display/intel_display_core.h
@@ -479,6 +479,12 @@ struct intel_display {
u32 pipestat_irq_mask[I915_MAX_PIPES];
} irq;
+ struct {
+ /* protected by wm.wm_mutex */
+ u16 linetime[I915_MAX_PIPES];
+ bool disable[I915_MAX_PIPES];
+ } pkgc;
+
struct {
wait_queue_head_t waitqueue;
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 9580672827b0..a588693a7094 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2904,64 +2904,75 @@ static int skl_wm_add_affected_planes(struct intel_atomic_state *state,
return 0;
}
-/*
- * If Fixed Refresh Rate or For VRR case Vmin = Vmax = Flipline:
- * Program DEEP PKG_C_LATENCY Pkg C with highest valid latency from
- * watermark level1 and up and above. If watermark level 1 is
- * invalid program it with all 1's.
- * Program PKG_C_LATENCY Added Wake Time = DSB execution time
- * If Variable Refresh Rate where Vmin != Vmax != Flipline:
- * Program DEEP PKG_C_LATENCY Pkg C with all 1's.
- * Program PKG_C_LATENCY Added Wake Time = 0
- */
+static int pkgc_max_linetime(struct intel_atomic_state *state)
+{
+ struct intel_display *display = to_intel_display(state);
+ const struct intel_crtc_state *crtc_state;
+ struct intel_crtc *crtc;
+ int i, max_linetime;
+
+ /*
+ * Apparenty the hardware uses WM_LINETIME internally for
+ * this stuff, compute everything based on that.
+ */
+ for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
+ display->pkgc.disable[crtc->pipe] = crtc_state->vrr.enable;
+ display->pkgc.linetime[crtc->pipe] = DIV_ROUND_UP(crtc_state->linetime, 8);
+ }
+
+ max_linetime = 0;
+ for_each_intel_crtc(display->drm, crtc) {
+ if (display->pkgc.disable[crtc->pipe])
+ return 0;
+
+ max_linetime = max(display->pkgc.linetime[crtc->pipe], max_linetime);
+ }
+
+ return max_linetime;
+}
+
void
intel_program_dpkgc_latency(struct intel_atomic_state *state)
{
struct intel_display *display = to_intel_display(state);
- struct intel_crtc *crtc;
- struct intel_crtc_state *new_crtc_state;
- u32 latency = LNL_PKG_C_LATENCY_MASK;
- u32 added_wake_time = 0;
- u32 max_linetime = 0;
- u32 clear, val;
- bool fixed_refresh_rate = false;
- int i;
+ int max_linetime, latency, added_wake_time = 0;
if (DISPLAY_VER(display) < 20)
return;
- for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
- if (!new_crtc_state->vrr.enable ||
- (new_crtc_state->vrr.vmin == new_crtc_state->vrr.vmax &&
- new_crtc_state->vrr.vmin == new_crtc_state->vrr.flipline))
- fixed_refresh_rate = true;
+ mutex_lock(&display->wm.wm_mutex);
- max_linetime = max(new_crtc_state->linetime, max_linetime);
- }
+ latency = skl_watermark_max_latency(display, 1);
- if (fixed_refresh_rate) {
- latency = skl_watermark_max_latency(display, 1);
+ /*
+ * Wa_22020432604
+ * "PKG_C_LATENCY Added Wake Time field is not working"
+ */
+ if (latency && (DISPLAY_VER(display) == 20 || DISPLAY_VER(display) == 30)) {
+ latency += added_wake_time;
+ added_wake_time = 0;
+ }
- /* Wa_22020432604 */
- if ((DISPLAY_VER(display) == 20 || DISPLAY_VER(display) == 30) && !latency) {
- latency += added_wake_time;
- added_wake_time = 0;
- }
+ max_linetime = pkgc_max_linetime(state);
- /* Wa_22020299601 */
- if ((latency && max_linetime) &&
- (DISPLAY_VER(display) == 20 || DISPLAY_VER(display) == 30)) {
- latency = max_linetime * DIV_ROUND_UP(latency, max_linetime);
- } else if (!latency) {
- latency = LNL_PKG_C_LATENCY_MASK;
- }
+ if (max_linetime == 0 || latency == 0) {
+ latency = REG_FIELD_GET(LNL_PKG_C_LATENCY_MASK,
+ LNL_PKG_C_LATENCY_MASK);
+ added_wake_time = 0;
+ } else {
+ /*
+ * Wa_22020299601
+ * "Increase the latency programmed in PKG_C_LATENCY Pkg C Latency to be a
+ * multiple of the pipeline time from WM_LINETIME"
+ */
+ latency = roundup(latency, max_linetime);
}
- clear = LNL_ADDED_WAKE_TIME_MASK | LNL_PKG_C_LATENCY_MASK;
- val = REG_FIELD_PREP(LNL_PKG_C_LATENCY_MASK, latency) |
- REG_FIELD_PREP(LNL_ADDED_WAKE_TIME_MASK, added_wake_time);
+ intel_de_write(display, LNL_PKG_C_LATENCY,
+ REG_FIELD_PREP(LNL_ADDED_WAKE_TIME_MASK, added_wake_time) |
+ REG_FIELD_PREP(LNL_PKG_C_LATENCY_MASK, latency));
- intel_de_rmw(display, LNL_PKG_C_LATENCY, clear, val);
+ mutex_unlock(&display->wm.wm_mutex);
}
static int
--
2.49.0
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