drm/amd/pm: Restore config space after reset

From Lijo Lazar
7e12479958532fb7f9ce5160dc7bb08513eef807 in linux-6.6.y/6.6.33
30d1cda8ce31ab49051ff7159280c542a738b23d in mainline linux

1 files changed, 28 insertions, 0 deletions

diff --git a/sys/dev/pci/drm/amd/pm/swsmu/smu13/smu_v13_0_6_ppt.c b/sys/dev/pci/drm/amd/pm/swsmu/smu13/smu_v13_0_6_ppt.c
index 37902e91847..ca4b8f9687d 100644
--- a/sys/dev/pci/drm/amd/pm/swsmu/smu13/smu_v13_0_6_ppt.c
+++ b/sys/dev/pci/drm/amd/pm/swsmu/smu13/smu_v13_0_6_ppt.c
@@ -2041,6 +2041,20 @@ static ssize_t smu_v13_0_6_get_gpu_metrics(struct smu_context *smu, void **table
 	return sizeof(struct gpu_metrics_v1_3);
 }
 
+static void smu_v13_0_6_restore_pci_config(struct smu_context *smu)
+{
+	STUB();
+#if notyet
+	struct amdgpu_device *adev = smu->adev;
+	int i;
+
+	for (i = 0; i < 16; i++)
+		pci_write_config_dword(adev->pdev, i * 4,
+				       adev->pdev->saved_config_space[i]);
+	pci_restore_msi_state(adev->pdev);
+#endif
+}
+
 static int smu_v13_0_6_mode2_reset(struct smu_context *smu)
 {
 	int ret = 0, index;
@@ -2062,6 +2076,20 @@ static int smu_v13_0_6_mode2_reset(struct smu_context *smu)
 	/* Restore the config space saved during init */
 	amdgpu_device_load_pci_state(adev->pdev);
 
+	/* Certain platforms have switches which assign virtual BAR values to
+	 * devices. OS uses the virtual BAR values and device behind the switch
+	 * is assgined another BAR value. When device's config space registers
+	 * are queried, switch returns the virtual BAR values. When mode-2 reset
+	 * is performed, switch is unaware of it, and will continue to return
+	 * the same virtual values to the OS.This affects
+	 * pci_restore_config_space() API as it doesn't write the value saved if
+	 * the current value read from config space is the same as what is
+	 * saved. As a workaround, make sure the config space is restored
+	 * always.
+	 */
+	if (!(adev->flags & AMD_IS_APU))
+		smu_v13_0_6_restore_pci_config(smu);
+
 	dev_dbg(smu->adev->dev, "wait for reset ack\n");
 	do {
 		ret = smu_cmn_wait_for_response(smu);