diff mbox series

[v3,2/2] drm/i915/display: Allow display PHYs to reset power state

Message ID 20250214140442.560378-3-mika.kahola@intel.com (mailing list archive)
State New
Headers show
Series drm/i915/display: Allow display PHYs to reset power state | expand

Commit Message

Mika Kahola Feb. 14, 2025, 2:04 p.m. UTC
The dedicated display PHYs reset to a power state that blocks S0ix,
increasing idle system power. After a system reset (cold boot,
S3/4/5, warm reset) if a dedicated PHY is not being brought up
shortly, use these steps to move the PHY to the lowest power state
to save power.

1. Follow the PLL Enable Sequence, using any valid frequency such as DP 1.62 GHz.
   This brings lanes out of reset and enables the PLL to allow powerdown to be moved
   to the Disable state.
2. Follow PLL Disable Sequence. This moves powerdown to the Disable state and disables the PLL.

v2: Rename WA function to more descriptive (Jani)
    For PTL, only port A needs this wa
    Add helpers to check presence of C10 phy and pll enabling (Imre)
v3: Rename wa function (Imre)
    Check return value of C10 pll tables readout (Imre)
    Use PLL request to check pll enabling (Imre)

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
---
 drivers/gpu/drm/i915/display/intel_cx0_phy.c  | 51 +++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_cx0_phy.h  |  1 +
 .../drm/i915/display/intel_display_reset.c    |  2 +
 drivers/gpu/drm/i915/display/intel_dpll_mgr.c |  3 ++
 4 files changed, 57 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
index 2c74d5cf54be..5f757134751e 100644
--- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
@@ -3559,3 +3559,54 @@  void intel_cx0pll_state_verify(struct intel_atomic_state *state,
 	else
 		intel_c20pll_state_verify(new_crtc_state, crtc, encoder, &mpll_hw_state.c20);
 }
+
+static bool intel_cx0_pll_is_enabled(struct intel_encoder *encoder)
+{
+	struct intel_display *display = to_intel_display(encoder);
+        struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
+	u8 lane = dig_port->lane_reversal ? INTEL_CX0_LANE1 : INTEL_CX0_LANE0;
+
+	return intel_de_read(display, XELPDP_PORT_CLOCK_CTL(display, encoder->port)) &
+	       intel_cx0_get_pclk_pll_request(lane);
+}
+
+/*
+ * WA 14022081154
+ * The dedicated display PHYs reset to a power state that blocks S0ix, increasing idle
+ * system power. After a system reset (cold boot, S3/4/5, warm reset) if a dedicated
+ * PHY is not being brought up shortly, use these steps to move the PHY to the lowest
+ * power state to save power. For PTL the workaround is needed only for port A. Port B
+ * is not connected.
+ *
+ * 1. Follow the PLL Enable Sequence, using any valid frequency such as DP 1.62 GHz.
+ *    This brings lanes out of reset and enables the PLL to allow powerdown to be moved
+ *    to the Disable state.
+ * 2. Follow PLL Disable Sequence. This moves powerdown to the Disable state and disables the PLL.
+ */
+void intel_cx0_pll_power_save_wa(struct intel_display *display)
+{
+	struct intel_encoder *encoder;
+
+	if (DISPLAY_VER(display) != 30)
+		return;
+
+	for_each_intel_encoder(display->drm, encoder) {
+		struct intel_cx0pll_state pll_state = {};
+		int port_clock = 162000;
+
+		if (!intel_encoder_is_c10phy(encoder))
+			continue;
+
+		if (intel_cx0_pll_is_enabled(encoder))
+			continue;
+
+		if (intel_c10pll_calc_state_from_table(encoder,
+						       mtl_c10_edp_tables,
+						       port_clock, true,
+						       &pll_state) < 0)
+			continue;
+
+		__intel_cx0pll_enable(encoder, &pll_state, true, port_clock, 4);
+		intel_cx0pll_disable(encoder);
+	}
+}
diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.h b/drivers/gpu/drm/i915/display/intel_cx0_phy.h
index 573fa7d3e88f..a8f811ca5e7b 100644
--- a/drivers/gpu/drm/i915/display/intel_cx0_phy.h
+++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.h
@@ -42,5 +42,6 @@  bool intel_cx0pll_compare_hw_state(const struct intel_cx0pll_state *a,
 void intel_cx0_phy_set_signal_levels(struct intel_encoder *encoder,
 				     const struct intel_crtc_state *crtc_state);
 int intel_mtl_tbt_calc_port_clock(struct intel_encoder *encoder);
+void intel_cx0_pll_power_save_wa(struct intel_display *display);
 
 #endif /* __INTEL_CX0_PHY_H__ */
diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.c b/drivers/gpu/drm/i915/display/intel_display_reset.c
index 093b386c95e8..a690968885bf 100644
--- a/drivers/gpu/drm/i915/display/intel_display_reset.c
+++ b/drivers/gpu/drm/i915/display/intel_display_reset.c
@@ -7,6 +7,7 @@ 
 
 #include "i915_drv.h"
 #include "intel_clock_gating.h"
+#include "intel_cx0_phy.h"
 #include "intel_display_driver.h"
 #include "intel_display_reset.h"
 #include "intel_display_types.h"
@@ -116,6 +117,7 @@  void intel_display_reset_finish(struct drm_i915_private *i915)
 		intel_pps_unlock_regs_wa(display);
 		intel_display_driver_init_hw(display);
 		intel_clock_gating_init(i915);
+		intel_cx0_pll_power_save_wa(display);
 		intel_hpd_init(i915);
 
 		ret = __intel_display_driver_resume(display, state, ctx);
diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
index eb3df25a308c..c825a507b905 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
@@ -27,6 +27,7 @@ 
 #include "bxt_dpio_phy_regs.h"
 #include "i915_drv.h"
 #include "i915_reg.h"
+#include "intel_cx0_phy.h"
 #include "intel_de.h"
 #include "intel_display_types.h"
 #include "intel_dkl_phy.h"
@@ -4571,6 +4572,8 @@  void intel_dpll_sanitize_state(struct intel_display *display)
 	struct intel_shared_dpll *pll;
 	int i;
 
+	intel_cx0_pll_power_save_wa(display);
+
 	for_each_shared_dpll(display, pll, i)
 		sanitize_dpll_state(display, pll);
 }