readl/writel is too expensive especially on Cortex A9 w/ outer L2 cache.
This introduces i2c read/write errors 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@xxxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 23628b7..e279948 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);
}
}
--
2.1.3
--
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