linux-kernel - [PATCH v3 9/9] PCI: dwc: Do not write to MSI control registers if the platform doesn't use it

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Date:   Wed, 13 Feb 2019 18:56:29 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Murali Karicheri <m-karicheri2@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
CC:     Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        <linux-pci@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 9/9] PCI: dwc: Do not write to MSI control registers if the platform doesn't use it

Platforms which populate msi_host_init, has it's own MSI controller
logic. Writing to MSI control registers on platforms which doesn't use
Designware's MSI controller logic might have side effects. To
be safe, do not write to MSI control registers if the platform uses
it's own MSI controller logic instead of Designware's MSI controller
logic.

Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
---
 .../pci/controller/dwc/pcie-designware-host.c | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 781735f06dea..2bc2fd582124 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -641,17 +641,19 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 
 	dw_pcie_setup(pci);
 
-	num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
-
-	/* Initialize IRQ Status array */
-	for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
-		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK +
-					(ctrl * MSI_REG_CTRL_BLOCK_SIZE),
-				    4, ~0);
-		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE +
-					(ctrl * MSI_REG_CTRL_BLOCK_SIZE),
-				    4, ~0);
-		pp->irq_status[ctrl] = 0;
+	if (!pp->ops->msi_host_init) {
+		num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
+
+		/* Initialize IRQ Status array */
+		for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
+			dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK +
+					    (ctrl * MSI_REG_CTRL_BLOCK_SIZE),
+					    4, ~0);
+			dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE +
+					    (ctrl * MSI_REG_CTRL_BLOCK_SIZE),
+					    4, ~0);
+			pp->irq_status[ctrl] = 0;
+		}
 	}
 
 	/* Setup RC BARs */
-- 
2.17.1