[PATCH] spi/rockchip: avoid uninitialized-use warning

[PATCH] spi/rockchip: avoid uninitialized-use warning

[Arnd Bergmann]

We currently get a warning about potentially uninitialized variables
in the rockchip spi driver, at least in certain toolchain versions:

spi/spi-rockchip.c: In function 'rockchip_spi_prepare_dma':
include/linux/dmaengine.h:796:2: warning: 'txdesc' may be used uninitialized in this function
include/linux/dmaengine.h:796:2: warning: 'rxdesc' may be used uninitialized in this function

The reason seems to be that gcc cannot know whether the value
of the rs->rx and rs->tx variables change between the two points
these are accessed.

The code is actually correct, but to make this clearer to the
compiler, this changes the conditionals to test for the local
rxdesc/txdesc variables instead, which it knows won't change.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index daabbabd26b0..1a777dc261d6 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -437,6 +437,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 	rs->state &= ~TXBUSY;
 	spin_unlock_irqrestore(&rs->lock, flags);
 
+	rxdesc = NULL;
 	if (rs->rx) {
 		rxconf.direction = rs->dma_rx.direction;
 		rxconf.src_addr = rs->dma_rx.addr;
@@ -453,6 +454,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		rxdesc->callback_param = rs;
 	}
 
+	txdesc = NULL;
 	if (rs->tx) {
 		txconf.direction = rs->dma_tx.direction;
 		txconf.dst_addr = rs->dma_tx.addr;
@@ -470,7 +472,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 	}
 
 	/* rx must be started before tx due to spi instinct */
-	if (rs->rx) {
+	if (rxdesc) {
 		spin_lock_irqsave(&rs->lock, flags);
 		rs->state |= RXBUSY;
 		spin_unlock_irqrestore(&rs->lock, flags);
@@ -478,7 +480,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		dma_async_issue_pending(rs->dma_rx.ch);
 	}
 
-	if (rs->tx) {
+	if (txdesc) {
 		spin_lock_irqsave(&rs->lock, flags);
 		rs->state |= TXBUSY;
 		spin_unlock_irqrestore(&rs->lock, flags);

[PATCH] spi/rockchip: avoid uninitialized-use warning

[Arnd Bergmann]

We currently get a warning about potentially uninitialized variables
in the rockchip spi driver, at least in certain toolchain versions:

spi/spi-rockchip.c: In function 'rockchip_spi_prepare_dma':
include/linux/dmaengine.h:796:2: warning: 'txdesc' may be used uninitialized in this function
include/linux/dmaengine.h:796:2: warning: 'rxdesc' may be used uninitialized in this function

The reason seems to be that gcc cannot know whether the value
of the rs->rx and rs->tx variables change between the two points
these are accessed.

The code is actually correct, but to make this clearer to the
compiler, this changes the conditionals to test for the local
rxdesc/txdesc variables instead, which it knows won't change.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index daabbabd26b0..1a777dc261d6 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -437,6 +437,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 	rs->state &= ~TXBUSY;
 	spin_unlock_irqrestore(&rs->lock, flags);
 
+	rxdesc = NULL;
 	if (rs->rx) {
 		rxconf.direction = rs->dma_rx.direction;
 		rxconf.src_addr = rs->dma_rx.addr;
@@ -453,6 +454,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		rxdesc->callback_param = rs;
 	}
 
+	txdesc = NULL;
 	if (rs->tx) {
 		txconf.direction = rs->dma_tx.direction;
 		txconf.dst_addr = rs->dma_tx.addr;
@@ -470,7 +472,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 	}
 
 	/* rx must be started before tx due to spi instinct */
-	if (rs->rx) {
+	if (rxdesc) {
 		spin_lock_irqsave(&rs->lock, flags);
 		rs->state |= RXBUSY;
 		spin_unlock_irqrestore(&rs->lock, flags);
@@ -478,7 +480,7 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		dma_async_issue_pending(rs->dma_rx.ch);
 	}
 
-	if (rs->tx) {
+	if (txdesc) {
 		spin_lock_irqsave(&rs->lock, flags);
 		rs->state |= TXBUSY;
 		spin_unlock_irqrestore(&rs->lock, flags);

[PATCH] spi: pl08x: do not select S3C64XX_PL080

[Arnd Bergmann]

The pl08x driver originally selected S3C64XX_PL080 to avoid having
the legacy Samsung DMA interfaces. Those are now gone, so the
select is no longer needed, but it now causes problems when
CONFIG_DMA_ENGINE is disabled:

arch/arm/plat-samsung/built-in.o: In function `s3c64xx_spi0_set_platdata':
:(.init.text+0x518): undefined reference to `pl08x_filter_id'

This simply removes the 'select' to avoid this problem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 9b81b39de54e..7727660e9702 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -470,7 +470,6 @@ config SPI_S3C24XX_FIQ
 config SPI_S3C64XX
 	tristate "Samsung S3C64XX series type SPI"
 	depends on (PLAT_SAMSUNG || ARCH_EXYNOS)
-	select S3C64XX_PL080 if ARCH_S3C64XX
 	help
 	  SPI driver for Samsung S3C64XX and newer SoCs.

[PATCH] spi: pl08x: do not select S3C64XX_PL080

[Arnd Bergmann]

The pl08x driver originally selected S3C64XX_PL080 to avoid having
the legacy Samsung DMA interfaces. Those are now gone, so the
select is no longer needed, but it now causes problems when
CONFIG_DMA_ENGINE is disabled:

arch/arm/plat-samsung/built-in.o: In function `s3c64xx_spi0_set_platdata':
:(.init.text+0x518): undefined reference to `pl08x_filter_id'

This simply removes the 'select' to avoid this problem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 9b81b39de54e..7727660e9702 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -470,7 +470,6 @@ config SPI_S3C24XX_FIQ
 config SPI_S3C64XX
 	tristate "Samsung S3C64XX series type SPI"
 	depends on (PLAT_SAMSUNG || ARCH_EXYNOS)
-	select S3C64XX_PL080 if ARCH_S3C64XX
 	help
 	  SPI driver for Samsung S3C64XX and newer SoCs.
 

Re: [PATCH] spi: pl08x: do not select S3C64XX_PL080

[Mark Brown]

[-- Attachment #1.1: Type: text/plain, Size: 309 bytes --]

On Wed, Jan 28, 2015 at 02:27:06PM +0100, Arnd Bergmann wrote:
> The pl08x driver originally selected S3C64XX_PL080 to avoid having
> the legacy Samsung DMA interfaces. Those are now gone, so the
> select is no longer needed, but it now causes problems when
> CONFIG_DMA_ENGINE is disabled:

Applied, thanks.

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[PATCH] spi: pl08x: do not select S3C64XX_PL080

[Mark Brown]

On Wed, Jan 28, 2015 at 02:27:06PM +0100, Arnd Bergmann wrote:
> The pl08x driver originally selected S3C64XX_PL080 to avoid having
> the legacy Samsung DMA interfaces. Those are now gone, so the
> select is no longer needed, but it now causes problems when
> CONFIG_DMA_ENGINE is disabled:

Applied, thanks.
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Re: [PATCH] spi/rockchip: avoid uninitialized-use warning

[Mark Brown]

[-- Attachment #1.1: Type: text/plain, Size: 222 bytes --]

On Wed, Jan 28, 2015 at 02:25:10PM +0100, Arnd Bergmann wrote:
> We currently get a warning about potentially uninitialized variables
> in the rockchip spi driver, at least in certain toolchain versions:

Applied, thanks.

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[PATCH] spi/rockchip: avoid uninitialized-use warning

[Mark Brown]

On Wed, Jan 28, 2015 at 02:25:10PM +0100, Arnd Bergmann wrote:
> We currently get a warning about potentially uninitialized variables
> in the rockchip spi driver, at least in certain toolchain versions:

Applied, thanks.
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