linux-kernel - [PATCH 2/8] MIPS: pci-rt2880: remove unneeded locks

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Message-Id: <20210413062146.389690-3-ilya.lipnitskiy@gmail.com>
Date:   Mon, 12 Apr 2021 23:21:40 -0700
From:   Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
        Sergey Ryazanov <ryazanov.s.a@...il.com>
Subject: [PATCH 2/8] MIPS: pci-rt2880: remove unneeded locks

Mirror pci-rt3883 fix from commit e5067c718b3a ("MIPS: pci-rt3883:
Remove odd locking in PCI config space access code"). pci-rt2880 shares
the driver layout with pci-rt3883 and the same reasons apply.

Caller (generic PCI code) already does proper locking, so no need to add
another one here. Local PCI read/write functions are never called
simultaneously, also they do not require synchronization with the PCI
controller ops, since they are used before the controller registration.

Suggested-by: Sergey Ryazanov <ryazanov.s.a@...il.com>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
---
 arch/mips/pci/pci-rt2880.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/arch/mips/pci/pci-rt2880.c b/arch/mips/pci/pci-rt2880.c
index 19f7860fb28b..b4ee07cbcf2a 100644
--- a/arch/mips/pci/pci-rt2880.c
+++ b/arch/mips/pci/pci-rt2880.c
@@ -41,7 +41,6 @@
 #define RT2880_PCI_REG_ARBCTL		0x80
 
 static void __iomem *rt2880_pci_base;
-static DEFINE_SPINLOCK(rt2880_pci_lock);
 
 static u32 rt2880_pci_reg_read(u32 reg)
 {
@@ -63,7 +62,6 @@ static inline u32 rt2880_pci_get_cfgaddr(unsigned int bus, unsigned int slot,
 static int rt2880_pci_config_read(struct pci_bus *bus, unsigned int devfn,
 				  int where, int size, u32 *val)
 {
-	unsigned long flags;
 	u32 address;
 	u32 data;
 	int busn = 0;
@@ -74,10 +72,8 @@ static int rt2880_pci_config_read(struct pci_bus *bus, unsigned int devfn,
 	address = rt2880_pci_get_cfgaddr(busn, PCI_SLOT(devfn), PCI_FUNC(devfn),
 					 where);
 
-	spin_lock_irqsave(&rt2880_pci_lock, flags);
 	rt2880_pci_reg_write(address, RT2880_PCI_REG_CONFIG_ADDR);
 	data = rt2880_pci_reg_read(RT2880_PCI_REG_CONFIG_DATA);
-	spin_unlock_irqrestore(&rt2880_pci_lock, flags);
 
 	switch (size) {
 	case 1:
@@ -97,7 +93,6 @@ static int rt2880_pci_config_read(struct pci_bus *bus, unsigned int devfn,
 static int rt2880_pci_config_write(struct pci_bus *bus, unsigned int devfn,
 				   int where, int size, u32 val)
 {
-	unsigned long flags;
 	u32 address;
 	u32 data;
 	int busn = 0;
@@ -108,7 +103,6 @@ static int rt2880_pci_config_write(struct pci_bus *bus, unsigned int devfn,
 	address = rt2880_pci_get_cfgaddr(busn, PCI_SLOT(devfn), PCI_FUNC(devfn),
 					 where);
 
-	spin_lock_irqsave(&rt2880_pci_lock, flags);
 	rt2880_pci_reg_write(address, RT2880_PCI_REG_CONFIG_ADDR);
 	data = rt2880_pci_reg_read(RT2880_PCI_REG_CONFIG_DATA);
 
@@ -127,7 +121,6 @@ static int rt2880_pci_config_write(struct pci_bus *bus, unsigned int devfn,
 	}
 
 	rt2880_pci_reg_write(data, RT2880_PCI_REG_CONFIG_DATA);
-	spin_unlock_irqrestore(&rt2880_pci_lock, flags);
 
 	return PCIBIOS_SUCCESSFUL;
 }
@@ -159,31 +152,25 @@ static struct pci_controller rt2880_pci_controller = {
 
 static inline u32 rt2880_pci_read_u32(unsigned long reg)
 {
-	unsigned long flags;
 	u32 address;
 	u32 ret;
 
 	address = rt2880_pci_get_cfgaddr(0, 0, 0, reg);
 
-	spin_lock_irqsave(&rt2880_pci_lock, flags);
 	rt2880_pci_reg_write(address, RT2880_PCI_REG_CONFIG_ADDR);
 	ret = rt2880_pci_reg_read(RT2880_PCI_REG_CONFIG_DATA);
-	spin_unlock_irqrestore(&rt2880_pci_lock, flags);
 
 	return ret;
 }
 
 static inline void rt2880_pci_write_u32(unsigned long reg, u32 val)
 {
-	unsigned long flags;
 	u32 address;
 
 	address = rt2880_pci_get_cfgaddr(0, 0, 0, reg);
 
-	spin_lock_irqsave(&rt2880_pci_lock, flags);
 	rt2880_pci_reg_write(address, RT2880_PCI_REG_CONFIG_ADDR);
 	rt2880_pci_reg_write(val, RT2880_PCI_REG_CONFIG_DATA);
-	spin_unlock_irqrestore(&rt2880_pci_lock, flags);
 }
 
 int pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
-- 
2.31.1