[PATCH] spi: pxa2xx: use DMA by default if supported

["Dan O'Donovan" <dan@xxxxxxxxxx>]

Currently, even if the PXA2xx SPI master supports DMA, it won't be
enabled unless (i) the slave device is enumerated through ACPI, or
(ii) the slave device is registered with board-specific
controller_data specified.  Even then, there isn't a field in the
controller_data that explicitly enables dma - it just gets enabled
if the master supports it and controller_data is non-NULL.

This means that drivers which register SPI devices on a bus without
awareness of this controller cannot avail of DMA performance gains.

This patch allows DMA transfers to be used if supported.

Signed-off-by: Dan O'Donovan <dan@xxxxxxxxxx>
---
 drivers/spi/spi-pxa2xx.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index fe07c05..27e0307 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1240,7 +1240,7 @@ static int setup(struct spi_device *spi)
 			chip->frm = spi->chip_select;
 		} else
 			chip->gpio_cs = -1;
-		chip->enable_dma = 0;
+		chip->enable_dma = drv_data->master_info->enable_dma;
 		chip->timeout = TIMOUT_DFLT;
 	}
 
@@ -1259,17 +1259,9 @@ static int setup(struct spi_device *spi)
 			tx_hi_thres = chip_info->tx_hi_threshold;
 		if (chip_info->rx_threshold)
 			rx_thres = chip_info->rx_threshold;
-		chip->enable_dma = drv_data->master_info->enable_dma;
 		chip->dma_threshold = 0;
 		if (chip_info->enable_loopback)
 			chip->cr1 = SSCR1_LBM;
-	} else if (ACPI_HANDLE(&spi->dev)) {
-		/*
-		 * Slave devices enumerated from ACPI namespace don't
-		 * usually have chip_info but we still might want to use
-		 * DMA with them.
-		 */
-		chip->enable_dma = drv_data->master_info->enable_dma;
 	}
 
 	chip->lpss_rx_threshold = SSIRF_RxThresh(rx_thres);
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html