[PATCH 1/3] ASoC: amd: ps: disable MSI on resume in ACP PCI driver

BIOS/firmware may re-enable MSI in PCI config space during system
level resume even though this driver only uses legacy INTx interrupts.
If MSI is left enabled with stale address/data registers, the device
will write interrupts to a bogus address causing IOMMU IO_PAGE_FAULT
and interrupt delivery failure.

Clear the MSI Enable bit before reinitializing the ACP hardware on
system level resume.

Fixes: 491628388005 ("ASoC: amd: ps: add callback functions for acp pci driver pm ops")
Signed-off-by: Vijendar Mukunda <[email protected]>
---
 sound/soc/amd/ps/pci-ps.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/sound/soc/amd/ps/pci-ps.c b/sound/soc/amd/ps/pci-ps.c
index 4ecda224157b..635832da45f9 100644
--- a/sound/soc/amd/ps/pci-ps.c
+++ b/sound/soc/amd/ps/pci-ps.c
@@ -693,8 +693,37 @@ static int snd_acp_runtime_resume(struct device *dev)
 	return acp_hw_runtime_resume(dev);
 }
 
+static void acp_disable_msi_on_resume(struct pci_dev *pdev)
+{
+	u16 control;
+
+	if (!pdev->msi_cap)
+		return;
+
+	pci_read_config_word(pdev, pdev->msi_cap + PCI_MSI_FLAGS, &control);
+	if (control & PCI_MSI_FLAGS_ENABLE) {
+		dev_warn(&pdev->dev,
+			 "ACP: MSI unexpectedly enabled after resume (flags=0x%04x), disabling\n",
+			 control);
+		control &= ~PCI_MSI_FLAGS_ENABLE;
+		pci_write_config_word(pdev, pdev->msi_cap + PCI_MSI_FLAGS, control);
+	}
+}
+
 static int snd_acp_resume(struct device *dev)
 {
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	/*
+	 * BIOS/firmware may re-enable MSI in PCI config space during
+	 * system resume even though this driver only uses legacy INTx
+	 * interrupts. If MSI is left enabled with stale address/data
+	 * registers, the device will write interrupts to a bogus address
+	 * causing IOMMU IO_PAGE_FAULT and interrupt delivery failure.
+	 * Explicitly clear the MSI Enable bit before reinitializing
+	 * the ACP hardware.
+	 */
+	acp_disable_msi_on_resume(pdev);
 	return acp_hw_resume(dev);
 }
 
-- 
2.48.1