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authorJisheng Zhang <jszhang@marvell.com>2014-12-11 07:26:41 +0100
committerWolfram Sang <wsa@the-dreams.de>2015-01-23 17:09:15 +0100
commit67105c5a94fbff6cc3a47e3ba65bacb3c706c5e6 (patch)
tree2138482025f36b3834f4ab244260125ae470ae11 /drivers/i2c
parenti2c: designware-pci: no need to provide clk_khz (diff)
downloadlinux-67105c5a94fbff6cc3a47e3ba65bacb3c706c5e6.tar.xz
linux-67105c5a94fbff6cc3a47e3ba65bacb3c706c5e6.zip
i2c: designware: use {readl|writel}_relaxed instead of readl/writel
readl/writel is too expensive especially on Cortex A9 w/ outer L2 cache. This introduces i2c read/write delays on Marvell BG2/BG2Q SoCs when there are heavy L2 cache maintenance operations at the same time. The driver does not perform DMA, so it's safe to use the relaxed version. From another side, the relaxed io accessor macros are available on all architectures now, so we can use the relaxed versions instead. Signed-off-by: Jisheng Zhang <jszhang@marvell.com> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-designware-core.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 23628b7bfb8d..e2799483dc45 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -170,10 +170,10 @@ u32 dw_readl(struct dw_i2c_dev *dev, int offset)
u32 value;
if (dev->accessor_flags & ACCESS_16BIT)
- value = readw(dev->base + offset) |
- (readw(dev->base + offset + 2) << 16);
+ value = readw_relaxed(dev->base + offset) |
+ (readw_relaxed(dev->base + offset + 2) << 16);
else
- value = readl(dev->base + offset);
+ value = readl_relaxed(dev->base + offset);
if (dev->accessor_flags & ACCESS_SWAP)
return swab32(value);
@@ -187,10 +187,10 @@ void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
b = swab32(b);
if (dev->accessor_flags & ACCESS_16BIT) {
- writew((u16)b, dev->base + offset);
- writew((u16)(b >> 16), dev->base + offset + 2);
+ writew_relaxed((u16)b, dev->base + offset);
+ writew_relaxed((u16)(b >> 16), dev->base + offset + 2);
} else {
- writel(b, dev->base + offset);
+ writel_relaxed(b, dev->base + offset);
}
}