[U-Boot] [PATCH v3 2/9] sunxi: pmic_bus: Decrease boot time by not writing duplicate data

[Priit Laes]

From: Olliver Schinagl <oliver at schinagl.nl>

When we clear a pmic_bus bit, we do a read-modify-write operation.
We waste some time however, by writing back the exact samea value
that was already set in the chip. Let us thus only do the write
in case data was changed.

Signed-off-by: Olliver Schinagl <oliver at schinagl.nl>
Signed-off-by: Priit Laes <plaes at plaes.org>

--
Changes since v2:
- Fix code for pmic_bus_setbits
---
 arch/arm/mach-sunxi/pmic_bus.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/mach-sunxi/pmic_bus.c b/arch/arm/mach-sunxi/pmic_bus.c
index 5d91d7e..dea42de 100644
--- a/arch/arm/mach-sunxi/pmic_bus.c
+++ b/arch/arm/mach-sunxi/pmic_bus.c
@@ -101,6 +101,9 @@ int pmic_bus_setbits(u8 reg, u8 bits)
 	if (ret)
 		return ret;
 
+	if ((val & bits) == bits)
+		return 0;
+
 	val |= bits;
 	return pmic_bus_write(reg, val);
 }
@@ -114,6 +117,9 @@ int pmic_bus_clrbits(u8 reg, u8 bits)
 	if (ret)
 		return ret;
 
+	if (!(val & bits))
+		return 0;
+
 	val &= ~bits;
 	return pmic_bus_write(reg, val);
 }
-- 
git-series 0.9.1