[PATCH v2] spi: nuc900: Fix setting multiple bits settings in register

[PATCH v2] spi: nuc900: Fix setting multiple bits settings in register

[Axel Lin]

The correct way to set multiple bits settings is always clear these
bit fields before set new settings.

Current code does not cause problem because the reset value of these
bit fields are 0, and these settings only set once during probe.

Signed-off-by: Axel Lin <axel.lin-8E1dMatC8ynQT0dZR+AlfA@public.gmane.org>
---
 drivers/spi/spi-nuc900.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/spi/spi-nuc900.c b/drivers/spi/spi-nuc900.c
index 675c210..a062a89 100644
--- a/drivers/spi/spi-nuc900.c
+++ b/drivers/spi/spi-nuc900.c
@@ -37,7 +37,9 @@
 /* usi register bit */
 #define ENINT		(0x01 << 17)
 #define ENFLG		(0x01 << 16)
+#define SLEEP		(0x0f << 12)
 #define TXNUM		(0x03 << 8)
+#define TXBITLEN	(0x1f << 3)
 #define TXNEG		(0x01 << 2)
 #define RXNEG		(0x01 << 1)
 #define LSB		(0x01 << 10)
@@ -115,8 +117,7 @@ static void nuc900_spi_chipsel(struct spi_device *spi, int value)
 	}
 }
 
-static void nuc900_spi_setup_txnum(struct nuc900_spi *hw,
-							unsigned int txnum)
+static void nuc900_spi_setup_txnum(struct nuc900_spi *hw, unsigned int txnum)
 {
 	unsigned int val;
 	unsigned long flags;
@@ -124,12 +125,7 @@ static void nuc900_spi_setup_txnum(struct nuc900_spi *hw,
 	spin_lock_irqsave(&hw->lock, flags);
 
 	val = __raw_readl(hw->regs + USI_CNT);
-
-	if (!txnum)
-		val &= ~TXNUM;
-	else
-		val |= txnum << 0x08;
-
+	val = (val & ~TXNUM) | (txnum << 0x08);
 	__raw_writel(val, hw->regs + USI_CNT);
 
 	spin_unlock_irqrestore(&hw->lock, flags);
@@ -145,9 +141,7 @@ static void nuc900_spi_setup_txbitlen(struct nuc900_spi *hw,
 	spin_lock_irqsave(&hw->lock, flags);
 
 	val = __raw_readl(hw->regs + USI_CNT);
-
-	val |= (txbitlen << 0x03);
-
+	val = (val & ~TXBITLEN) | (txbitlen << 0x03);
 	__raw_writel(val, hw->regs + USI_CNT);
 
 	spin_unlock_irqrestore(&hw->lock, flags);
@@ -284,11 +278,7 @@ static void nuc900_set_sleep(struct nuc900_spi *hw, unsigned int sleep)
 	spin_lock_irqsave(&hw->lock, flags);
 
 	val = __raw_readl(hw->regs + USI_CNT);
-
-	if (sleep)
-		val |= (sleep << 12);
-	else
-		val &= ~(0x0f << 12);
+	val = (val & ~SLEEP) | (sleep << 12);
 	__raw_writel(val, hw->regs + USI_CNT);
 
 	spin_unlock_irqrestore(&hw->lock, flags);
-- 
1.8.3.2



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Re: [PATCH v2] spi: nuc900: Fix setting multiple bits settings in register

[Mark Brown]

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On Fri, Mar 21, 2014 at 10:40:23PM +0800, Axel Lin wrote:
> The correct way to set multiple bits settings is always clear these
> bit fields before set new settings.
> 
> Current code does not cause problem because the reset value of these
> bit fields are 0, and these settings only set once during probe.

This doesn't seem to apply against current code, can you please check
and resend?

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Re: [PATCH v2] spi: nuc900: Fix setting multiple bits settings in register

[Axel Lin]

2014-03-27 0:48 GMT+08:00 Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>:
> On Fri, Mar 21, 2014 at 10:40:23PM +0800, Axel Lin wrote:
>> The correct way to set multiple bits settings is always clear these
>> bit fields before set new settings.
>>
>> Current code does not cause problem because the reset value of these
>> bit fields are 0, and these settings only set once during probe.
>
> This doesn't seem to apply against current code, can you please check
> and resend?
It's because v1 is applied.
I personally do not have strong preference between v1 and v2.
Is it ok to keep it as is since it's applied.
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