linux-kernel - [PATCH V8 03/15] PCI: dwc: Perform dbi regs write lock towards the end

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Date:   Sun, 26 May 2019 10:07:39 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     <lorenzo.pieralisi@....com>, <bhelgaas@...gle.com>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <kishon@...com>, <catalin.marinas@....com>, <will.deacon@....com>,
        <jingoohan1@...il.com>, <gustavo.pimentel@...opsys.com>
CC:     <mperttunen@...dia.com>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kthota@...dia.com>,
        <mmaddireddy@...dia.com>, <vidyas@...dia.com>, <sagar.tv@...il.com>
Subject: [PATCH V8 03/15] PCI: dwc: Perform dbi regs write lock towards the end

Remove multiple write enable and disable sequences of dbi registers as
Tegra194 implements writes to BAR-0 register (offset: 0x10) controlled by
DBI write-lock enable bit thereby not allowing any further writes to BAR-0
register in config space to take place. Hence enabling write permission at
the start of function and disabling the same only towards the end.

Signed-off-by: Vidya Sagar <vidyas@...dia.com>
Reviewed-by: Thierry Reding <treding@...dia.com>
---
Changes since [v7]:
* None

Changes since [v6]:
* None

Changes since [v5]:
* Moved write enable to the beginning of the API and write disable to the end

Changes since [v4]:
* None

Changes since [v3]:
* None

Changes since [v2]:
* None

Changes since [v1]:
* None

 drivers/pci/controller/dwc/pcie-designware-host.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index f93252d0da5b..d3156446ff27 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -628,6 +628,12 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 	u32 val, ctrl, num_ctrls;
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 
+	/*
+	 * Enable DBI read-only registers for writing/updating configuration.
+	 * Write permission gets disabled towards the end of this function.
+	 */
+	dw_pcie_dbi_ro_wr_en(pci);
+
 	dw_pcie_setup(pci);
 
 	if (!pp->ops->msi_host_init) {
@@ -650,12 +656,10 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_1, 0x00000000);
 
 	/* Setup interrupt pins */
-	dw_pcie_dbi_ro_wr_en(pci);
 	val = dw_pcie_readl_dbi(pci, PCI_INTERRUPT_LINE);
 	val &= 0xffff00ff;
 	val |= 0x00000100;
 	dw_pcie_writel_dbi(pci, PCI_INTERRUPT_LINE, val);
-	dw_pcie_dbi_ro_wr_dis(pci);
 
 	/* Setup bus numbers */
 	val = dw_pcie_readl_dbi(pci, PCI_PRIMARY_BUS);
@@ -687,15 +691,13 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 
 	dw_pcie_wr_own_conf(pp, PCI_BASE_ADDRESS_0, 4, 0);
 
-	/* Enable write permission for the DBI read-only register */
-	dw_pcie_dbi_ro_wr_en(pci);
 	/* Program correct class for RC */
 	dw_pcie_wr_own_conf(pp, PCI_CLASS_DEVICE, 2, PCI_CLASS_BRIDGE_PCI);
-	/* Better disable write permission right after the update */
-	dw_pcie_dbi_ro_wr_dis(pci);
 
 	dw_pcie_rd_own_conf(pp, PCIE_LINK_WIDTH_SPEED_CONTROL, 4, &val);
 	val |= PORT_LOGIC_SPEED_CHANGE;
 	dw_pcie_wr_own_conf(pp, PCIE_LINK_WIDTH_SPEED_CONTROL, 4, val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
 }
 EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
-- 
2.17.1