linux-kernel - [PATCH v2 1/3] PCI: aardvark: Fix reading MSI interrupt number

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Message-Id: <20210823164033.27491-2-pali@kernel.org>
Date:   Mon, 23 Aug 2021 18:40:31 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh@...nel.org>
Cc:     Krzysztof Wilczyński <kw@...ux.com>,
        Marek Behún <kabel@...nel.org>,
        "Marc Zyngier" <maz@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] PCI: aardvark: Fix reading MSI interrupt number

Experiments showed that in register PCIE_MSI_PAYLOAD_REG is stored number
of the last received MSI interrupt and not number of MSI interrupt which
belongs to msi_idx bit. Therefore this implies that aardvark HW can cache
only bits [4:0] of received MSI interrupts with effectively means that it
supports only MSI interrupts with numbers 0-31.

Do not read PCIE_MSI_PAYLOAD_REG register for determining MSI interrupt
number. Instead ensure that pci-aardvark.c configures only MSI numbers in
range 0-31 and then msi_idx contains correct received MSI number.

Signed-off-by: Pali Rohár <pali@...nel.org>
Cc: stable@...r.kernel.org
---
 drivers/pci/controller/pci-aardvark.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 48fbfa7eb24c..81c4a9ff91a3 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -1232,7 +1232,6 @@ static void advk_pcie_remove_irq_domain(struct advk_pcie *pcie)
 static void advk_pcie_handle_msi(struct advk_pcie *pcie)
 {
 	u32 msi_val, msi_mask, msi_status, msi_idx;
-	u16 msi_data;
 	int virq;
 
 	msi_mask = advk_readl(pcie, PCIE_MSI_MASK_REG);
@@ -1243,17 +1242,13 @@ static void advk_pcie_handle_msi(struct advk_pcie *pcie)
 		if (!(BIT(msi_idx) & msi_status))
 			continue;
 
-		/*
-		 * msi_idx contains bits [4:0] of the msi_data and msi_data
-		 * contains 16bit MSI interrupt number from MSI inner domain
-		 */
 		advk_writel(pcie, BIT(msi_idx), PCIE_MSI_STATUS_REG);
-		msi_data = advk_readl(pcie, PCIE_MSI_PAYLOAD_REG) & PCIE_MSI_DATA_MASK;
-		virq = irq_find_mapping(pcie->msi_inner_domain, msi_data);
+
+		virq = irq_find_mapping(pcie->msi_inner_domain, msi_idx);
 		if (virq)
 			generic_handle_irq(virq);
 		else
-			dev_err_ratelimited(&pcie->pdev->dev, "unexpected MSI 0x%04hx\n", msi_data);
+			dev_err_ratelimited(&pcie->pdev->dev, "unexpected MSI 0x%02x\n", msi_idx);
 	}
 
 	advk_writel(pcie, PCIE_ISR0_MSI_INT_PENDING,
-- 
2.20.1