spi/omap2_mcspi: Verify TX reg is empty after TX only xfer with DMA

Commit Message

Ilkka Koskinen Oct. 19, 2010, 2:07 p.m. UTC

None

Patch

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index b3a94ca..a2e053c 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -296,6 +296,19 @@  static int omap2_mcspi_enable_clocks(struct omap2_mcspi *mcspi)
 	return 0;
 }
 
+static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
+{
+	unsigned long timeout;
+
+	timeout = jiffies + msecs_to_jiffies(1000);
+	while (!(__raw_readl(reg) & bit)) {
+		if (time_after(jiffies, timeout))
+			return -1;
+		cpu_relax();
+	}
+	return 0;
+}
+
 static unsigned
 omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
 {
@@ -309,11 +322,14 @@  omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
 	u32			l;
 	u8			* rx;
 	const u8		* tx;
+	void __iomem		*chstat_reg;
 
 	mcspi = spi_master_get_devdata(spi->master);
 	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
 	l = mcspi_cached_chconf0(spi);
 
+	chstat_reg = cs->base + OMAP2_MCSPI_CHSTAT0;
+
 	count = xfer->len;
 	c = count;
 	word_len = cs->word_len;
@@ -382,6 +398,16 @@  omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
 	if (tx != NULL) {
 		wait_for_completion(&mcspi_dma->dma_tx_completion);
 		dma_unmap_single(NULL, xfer->tx_dma, count, DMA_TO_DEVICE);
+
+		/* for TX_ONLY mode, be sure all words have shifted out */
+		if (rx == NULL) {
+			if (mcspi_wait_for_reg_bit(chstat_reg,
+						OMAP2_MCSPI_CHSTAT_TXS) < 0)
+				dev_err(&spi->dev, "TXS timed out\n");
+			else if (mcspi_wait_for_reg_bit(chstat_reg,
+						OMAP2_MCSPI_CHSTAT_EOT) < 0)
+				dev_err(&spi->dev, "EOT timed out\n");
+		}
 	}
 
 	if (rx != NULL) {
@@ -435,19 +461,6 @@  omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
 	return count;
 }
 
-static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
-{
-	unsigned long timeout;
-
-	timeout = jiffies + msecs_to_jiffies(1000);
-	while (!(__raw_readl(reg) & bit)) {
-		if (time_after(jiffies, timeout))
-			return -1;
-		cpu_relax();
-	}
-	return 0;
-}
-
 static unsigned
 omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 {