[Intel-gfx] [PATCH v2] drm/i915/gt: prevent forcewake releases during BAR resize

[Andrzej Hajda <andrzej.hajda@intel.com>]

Tests on DG2 machines show that releasing forcewakes during BAR resize
results later in forcewake ack timeouts. Since forcewakes can be realeased
asynchronously the simplest way to prevent it is to get all forcewakes
for duration of BAR resizing.

v2: hold rpm as well during resizing (Rodrigo)

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
Please ignore resend of v1, my mistake.

Regards
Andrzej
---
 drivers/gpu/drm/i915/gt/intel_region_lmem.c | 25 +++++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
index 89fdfc67f8d1e0..2a3217e2890fc7 100644
--- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
@@ -54,6 +54,7 @@ static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t
 	struct resource *root_res;
 	resource_size_t rebar_size;
 	resource_size_t current_size;
+	intel_wakeref_t wakeref;
 	u32 pci_cmd;
 	int i;
 
@@ -102,15 +103,25 @@ static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t
 		return;
 	}
 
-	/* First disable PCI memory decoding references */
-	pci_read_config_dword(pdev, PCI_COMMAND, &pci_cmd);
-	pci_write_config_dword(pdev, PCI_COMMAND,
-			       pci_cmd & ~PCI_COMMAND_MEMORY);
+	/*
+	 * Releasing forcewake during BAR resizing results in later forcewake
+	 * ack timeouts and former can happen any time - it is asynchronous.
+	 * Grabbing all forcewakes prevents it.
+	 */
+	with_intel_runtime_pm(i915->uncore.rpm, wakeref) {
+		intel_uncore_forcewake_get(&i915->uncore, FORCEWAKE_ALL);
 
-	_resize_bar(i915, GEN12_LMEM_BAR, rebar_size);
+		/* First disable PCI memory decoding references */
+		pci_read_config_dword(pdev, PCI_COMMAND, &pci_cmd);
+		pci_write_config_dword(pdev, PCI_COMMAND,
+				       pci_cmd & ~PCI_COMMAND_MEMORY);
 
-	pci_assign_unassigned_bus_resources(pdev->bus);
-	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
+		_resize_bar(i915, GEN12_LMEM_BAR, rebar_size);
+
+		pci_assign_unassigned_bus_resources(pdev->bus);
+		pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
+		intel_uncore_forcewake_put(&i915->uncore, FORCEWAKE_ALL);
+	}
 }
 #else
 static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t lmem_size) {}
-- 
2.34.1