spi/rockchip: avoid uninitialized-use warning

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.

index daabbabd26b0..1a777dc261d6 100644
@@ -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);

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.

index 9b81b39de54e..7727660e9702 100644
@@ -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.
 

Applied, thanks.
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Applied, thanks.
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