[Intel-gfx] [PATCH] drm/i915/dg1: Disable D3 for gfx's VSP

[Anshuman Gupta]

When DG1 gfx pci endpoint's parent upstream bridge (VSP) enters
to D3, any direct memory read from lmem returns with 0xff.
DG1 requires i915 driven runtime resume in order to read properly
from lmem, DG1 is unable to wakeup from local memory reads.
This may breaks using mmap() with lmem object on DG1 as it
relies on mercy of i915 driven runtime resume.

Let's not break using mmap() for lmem object on DG1.
Using pci_d3cold_disable(i915) accordingly to disable D3 for
upstream bridge.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6331
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
---
 drivers/gpu/drm/i915/intel_runtime_pm.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 6ed5786bcd29..671009fd351a 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -559,6 +559,7 @@ void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)
 	struct drm_i915_private *i915 = container_of(rpm,
 						     struct drm_i915_private,
 						     runtime_pm);
+	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 	struct device *kdev = rpm->kdev;
 
 	/*
@@ -574,6 +575,9 @@ void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)
 	pm_runtime_set_autosuspend_delay(kdev, 10000); /* 10s */
 	pm_runtime_mark_last_busy(kdev);
 
+	if (IS_DG1(i915))
+		pci_d3cold_disable(pdev);
+
 	/*
 	 * Take a permanent reference to disable the RPM functionality and drop
 	 * it only when unloading the driver. Use the low level get/put helpers,
@@ -607,12 +611,16 @@ void intel_runtime_pm_disable(struct intel_runtime_pm *rpm)
 	struct drm_i915_private *i915 = container_of(rpm,
 						     struct drm_i915_private,
 						     runtime_pm);
+	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 	struct device *kdev = rpm->kdev;
 
 	/* Transfer rpm ownership back to core */
 	drm_WARN(&i915->drm, pm_runtime_get_sync(kdev) < 0,
 		 "Failed to pass rpm ownership back to core\n");
 
+	if (IS_DG1(i915))
+		pci_d3cold_enable(pdev);
+
 	pm_runtime_dont_use_autosuspend(kdev);
 
 	if (!rpm->available)
-- 
2.26.2