linux-kernel - [PATCH] PCI: tegra: Restore MSI enable state on resume

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Date:   Tue, 20 Apr 2021 14:05:26 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Cc:     kernel-team@...roid.com, Jon Hunter <jonathanh@...dia.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Thierry Reding <thierry.reding@...il.com>
Subject: [PATCH] PCI: tegra: Restore MSI enable state on resume

When going into suspend, the Tegra MSI controller loses its
state. Restore the MSI allocation on resume so that PCI devices
are usable again.

Reported-by: Jon Hunter <jonathanh@...dia.com>
Tested-by: Jon Hunter <jonathanh@...dia.com>
Fixes: 973a28677e39 ("PCI: tegra: Convert to MSI domains")
Signed-off-by: Marc Zyngier <maz@...nel.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Thierry Reding <thierry.reding@...il.com>
---
 drivers/pci/controller/pci-tegra.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
index eaba7b2fab4a..507b23d43ad1 100644
--- a/drivers/pci/controller/pci-tegra.c
+++ b/drivers/pci/controller/pci-tegra.c
@@ -1802,13 +1802,19 @@ static void tegra_pcie_enable_msi(struct tegra_pcie *pcie)
 {
 	const struct tegra_pcie_soc *soc = pcie->soc;
 	struct tegra_msi *msi = &pcie->msi;
-	u32 reg;
+	u32 reg, msi_state[INT_PCI_MSI_NR / 32];
+	int i;
 
 	afi_writel(pcie, msi->phys >> soc->msi_base_shift, AFI_MSI_FPCI_BAR_ST);
 	afi_writel(pcie, msi->phys, AFI_MSI_AXI_BAR_ST);
 	/* this register is in 4K increments */
 	afi_writel(pcie, 1, AFI_MSI_BAR_SZ);
 
+	/* Restore the MSI allocation state */
+	bitmap_to_arr32(msi_state, msi->used, INT_PCI_MSI_NR);
+	for (i = 0; i < ARRAY_SIZE(msi_state); i++)
+		afi_writel(pcie, msi_state[i], AFI_MSI_EN_VEC(i));
+
 	/* and unmask the MSI interrupt */
 	reg = afi_readl(pcie, AFI_INTR_MASK);
 	reg |= AFI_INTR_MASK_MSI_MASK;
-- 
2.30.2