linux-kernel - [PATCH] PCI: designware: check for iATU unroll support after initializing host

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Date:   Fri, 14 Oct 2016 23:54:55 +0200
From:   Niklas Cassel <niklas.cassel@...s.com>
To:     <jingoohan1@...il.com>, <pratyush.anand@...il.com>,
        <bhelgaas@...gle.com>, <Joao.Pinto@...opsys.com>
CC:     <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Niklas Cassel <niklass@...s.com>
Subject: [PATCH] PCI: designware: check for iATU unroll support after initializing host

From: Niklas Cassel <niklas.cassel@...s.com>

dw_pcie_iatu_unroll_enabled reads a dbi_base register.
Reading any dbi_base register before pp->ops->host_init has been called
causes "imprecise external abort" on platforms like ARTPEC-6, where the
PCIe module is disabled at boot and first enabled in pp->ops->host_init.
Move dw_pcie_iatu_unroll_enabled to dw_pcie_setup_rc, since it is after
pp->ops->host_init, but before pp->iatu_unroll_enabled is actually used.

Fixes: a0601a470537 ("PCI: designware: Add iATU Unroll feature")
Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
---
 drivers/pci/host/pcie-designware.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index 035f50c03281..bed19994c1e9 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -637,8 +637,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
 		}
 	}
 
-	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
-
 	if (pp->ops->host_init)
 		pp->ops->host_init(pp);
 
@@ -809,6 +807,11 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 {
 	u32 val;
 
+	/* get iATU unroll support */
+	pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
+	dev_dbg(pp->dev, "iATU unroll: %s\n",
+		pp->iatu_unroll_enabled ? "enabled" : "disabled");
+
 	/* set the number of lanes */
 	val = dw_pcie_readl_rc(pp, PCIE_PORT_LINK_CONTROL);
 	val &= ~PORT_LINK_MODE_MASK;
-- 
2.1.4