---

yaml
---
r: 154590
b: refs/heads/master
c: 70d6027
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b55f627feeb9d48fdbde3835e18afbc76712e49b
+refs/heads/master: 70d6027ff2bc8bab180273b77e7ab3e8a62cca51

trunk/drivers/mmc/host/mmc_spi.c

@@ -1313,6 +1313,12 @@ static int mmc_spi_probe(struct spi_device *spi)
 	struct mmc_spi_host	*host;
 	int			status;
 
+	/* We rely on full duplex transfers, mostly to reduce
+	 * per-transfer overheads (by making fewer transfers).
+	 */
+	if (spi->master->flags & SPI_MASTER_HALF_DUPLEX)
+		return -EINVAL;
+
 	/* MMC and SD specs only seem to care that sampling is on the
 	 * rising edge ... meaning SPI modes 0 or 3.  So either SPI mode
 	 * should be legit.  We'll use mode 0 since the steady state is 0,

trunk/drivers/spi/omap_uwire.c

@@ -514,6 +514,8 @@ static int __init uwire_probe(struct platform_device *pdev)
 	/* the spi->mode bits understood by this driver: */
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 
+	master->flags = SPI_MASTER_HALF_DUPLEX;
+
 	master->bus_num = 2;	/* "official" */
 	master->num_chipselect = 4;
 	master->setup = uwire_setup;

trunk/include/linux/spi/spi.h

@@ -250,6 +250,10 @@ struct spi_master {
 	/* spi_device.mode flags understood by this controller driver */
 	u16			mode_bits;
 
+	/* other constraints relevant to this driver */
+	u16			flags;
+#define SPI_MASTER_HALF_DUPLEX	BIT(0)		/* can't do full duplex */
+
 	/* Setup mode and clock, etc (spi driver may call many times).
 	 *
 	 * IMPORTANT:  this may be called when transfers to another