linux-kernel - [PATCH v2 1/5] PCI: mvebu: move clock enable before register access

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Date:	Tue, 13 Aug 2013 14:25:20 +0200
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Cc:	Russell King <linux@....linux.org.uk>,
	Jason Cooper <jason@...edaemon.net>,
	Andrew Lunn <andrew@...n.ch>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Thierry Reding <thierry.reding@...il.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-pci@...r.kernel.org
Subject: [PATCH v2 1/5] PCI: mvebu: move clock enable before register access

The clock passed to PCI controller found on MVEBU SoCs may come from a
clock gate. This requires the clock to be enabled before any registers
are accessed. Therefore, move the clock enable before register iomap to
ensure it is enabled.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
---
Changelog:
v1->v2:
- remove iounmap, add clk_disable_unprepare on failure
  (Reported by Thomas Pettazoni)

Cc: Russell King <linux@....linux.org.uk>
Cc: Jason Cooper <jason@...edaemon.net>
Cc: Andrew Lunn <andrew@...n.ch>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc: Thierry Reding <thierry.reding@...il.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-pci@...r.kernel.org
---
 drivers/pci/host/pci-mvebu.c |   25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
index 6aa0daf..1533fda 100644
--- a/drivers/pci/host/pci-mvebu.c
+++ b/drivers/pci/host/pci-mvebu.c
@@ -897,10 +897,22 @@ static int __init mvebu_pcie_probe(struct platform_device *pdev)
 			continue;
 		}
 
+		port->clk = of_clk_get_by_name(child, NULL);
+		if (IS_ERR(port->clk)) {
+			dev_err(&pdev->dev, "PCIe%d.%d: cannot get clock\n",
+			       port->port, port->lane);
+			continue;
+		}
+
+		ret = clk_prepare_enable(port->clk);
+		if (ret)
+			continue;
+
 		port->base = mvebu_pcie_map_registers(pdev, child, port);
 		if (!port->base) {
 			dev_err(&pdev->dev, "PCIe%d.%d: cannot map registers\n",
 				port->port, port->lane);
+			clk_disable_unprepare(port->clk);
 			continue;
 		}
 
@@ -916,22 +928,9 @@ static int __init mvebu_pcie_probe(struct platform_device *pdev)
 				 port->port, port->lane);
 		}
 
-		port->clk = of_clk_get_by_name(child, NULL);
-		if (IS_ERR(port->clk)) {
-			dev_err(&pdev->dev, "PCIe%d.%d: cannot get clock\n",
-			       port->port, port->lane);
-			iounmap(port->base);
-			port->haslink = 0;
-			continue;
-		}
-
 		port->dn = child;
-
-		clk_prepare_enable(port->clk);
 		spin_lock_init(&port->conf_lock);
-
 		mvebu_sw_pci_bridge_init(port);
-
 		i++;
 	}
 
-- 
1.7.10.4

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