[Intel-gfx] [RFC v3] drm/i915/tgl: Suppress DC5/DC6 around DSB usage

[Matt Roper]

There are reports of unexpected DSB busy/timeout happening after IGT
tests finish running that apparently go away when the DMC firmware isn't
loaded.  The bspec doesn't say anything specific about DSB needing us to
exit DC5/DC6, but let's try adding DSB usage to the "DC off" list and
see if that changes the behavior.

v2: Include intel_wakeref.h from intel_dsb.h to ensure the header stays
    self-contained.  (CI)

v3: Move intel_display_power_get() call earlier to cover cases where
    dsb->refcount is already non-zero and we return early.  Also don't
    drop the wakeref at the end of the 'get' routine; wait until the
    'put' for that, even in error conditions.  (Swati)

Cc: Swati Sharma <swati2.sharma at intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
Reviewed-by(v1): José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display_power.c |  3 +++
 drivers/gpu/drm/i915/display/intel_display_power.h |  1 +
 drivers/gpu/drm/i915/display/intel_dsb.c           | 10 ++++------
 drivers/gpu/drm/i915/display/intel_dsb.h           |  2 ++
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 761be9fcaf10..99e6afda2db9 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -150,6 +150,8 @@ intel_display_power_domain_str(enum intel_display_power_domain domain)
 		return "GT_IRQ";
 	case POWER_DOMAIN_DPLL_DC_OFF:
 		return "DPLL_DC_OFF";
+	case POWER_DOMAIN_DSB:
+		return "DSB";
 	default:
 		MISSING_CASE(domain);
 		return "?";
@@ -2679,6 +2681,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 	BIT_ULL(POWER_DOMAIN_AUX_A) |			\
 	BIT_ULL(POWER_DOMAIN_AUX_B) |			\
 	BIT_ULL(POWER_DOMAIN_AUX_C) |			\
+	BIT_ULL(POWER_DOMAIN_DSB) |			\
 	BIT_ULL(POWER_DOMAIN_INIT))
 
 #define TGL_DDI_IO_D_TC1_POWER_DOMAINS (	\
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 2608a65af7fa..5e8136c65e02 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -77,6 +77,7 @@ enum intel_display_power_domain {
 	POWER_DOMAIN_GT_IRQ,
 	POWER_DOMAIN_DPLL_DC_OFF,
 	POWER_DOMAIN_INIT,
+	POWER_DOMAIN_DSB,
 
 	POWER_DOMAIN_NUM,
 };
diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index ada006a690df..b47c31fa2551 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -103,16 +103,15 @@ intel_dsb_get(struct intel_crtc *crtc)
 	struct drm_i915_gem_object *obj;
 	struct i915_vma *vma;
 	u32 *buf;
-	intel_wakeref_t wakeref;
 
 	if (!HAS_DSB(i915))
 		return dsb;
 
+	dsb->wakeref = intel_display_power_get(i915, POWER_DOMAIN_DSB);
+
 	if (dsb->refcount++ != 0)
 		return dsb;
 
-	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
-
 	obj = i915_gem_object_create_internal(i915, DSB_BUF_SIZE);
 	if (IS_ERR(obj)) {
 		DRM_ERROR("Gem object creation failed\n");
@@ -143,9 +142,6 @@ intel_dsb_get(struct intel_crtc *crtc)
 	 * corresponding intel_dsb_put(): the important error message will
 	 * already be logged above.
 	 */
-
-	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
-
 	return dsb;
 }
 
@@ -174,6 +170,8 @@ void intel_dsb_put(struct intel_dsb *dsb)
 		dsb->free_pos = 0;
 		dsb->ins_start_offset = 0;
 	}
+
+	intel_display_power_put(i915, POWER_DOMAIN_DSB, dsb->wakeref);
 }
 
 /**
diff --git a/drivers/gpu/drm/i915/display/intel_dsb.h b/drivers/gpu/drm/i915/display/intel_dsb.h
index 395ef9ce558e..ffb5afa935b7 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.h
+++ b/drivers/gpu/drm/i915/display/intel_dsb.h
@@ -9,6 +9,7 @@
 #include <linux/types.h>
 
 #include "i915_reg.h"
+#include "intel_wakeref.h"
 
 struct intel_crtc;
 struct i915_vma;
@@ -26,6 +27,7 @@ struct intel_dsb {
 	enum dsb_id id;
 	u32 *cmd_buf;
 	struct i915_vma *vma;
+	intel_wakeref_t wakeref;
 
 	/*
 	 * free_pos will point the first free entry position
-- 
2.23.0