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[RESEND] spi: s3c64xx: Don't request/release DMA channels for each SPI transfer

Message ID 1483958170-17270-1-git-send-email-m.szyprowski@samsung.com (mailing list archive)
State Not Applicable
Headers show

Commit Message

Marek Szyprowski Jan. 9, 2017, 10:36 a.m. UTC 
Requesting a DMA channel might be a time consuming operation, so there is
no need to acquire and release DMA channel for each SPI transfer.
DMA channels can be requested during driver probe and kept all the time,
also because there are no shared nor dynamically allocated channels on
Samsung S3C/S5P/Exynos platforms.

While moving dma_requrest_slave_channel calls, lets switch to
dma_request_slave_channel_reason(), which returns error codes on failure,
which can be properly propagated to the caller (this for example defers
SPI probe when DMA controller is not yet available).

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Andi Shyti <andi.shyti@samsung.com>
Tested-by: Andi Shyti <andi.shyti@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
---
This patch depends on commit 6f8dc9d481759b428a8cb6a17b83821451415ba9
("spi: s3c64xx: Do not use platform_data for DMA parameters"), which is
already in Linux v4.10-rc1 and came there through dma-engine tree. For
merging to spi-next tree, it requires merging first v4.10-rc1.

Resend reason:
- collected tags
- added information about patch dependency
---
 drivers/spi/spi-s3c64xx.c | 57 ++++++++++++++++++++++++-----------------------
 1 file changed, 29 insertions(+), 28 deletions(-)
diff mbox

Patch

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 28dfdce4beae..849ee82483e4 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -341,43 +341,16 @@  static void s3c64xx_spi_set_cs(struct spi_device *spi, bool enable)
 static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 {
 	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi);
-	struct device *dev = &sdd->pdev->dev;
 
 	if (is_polling(sdd))
 		return 0;
 
-	/* Acquire DMA channels */
-	sdd->rx_dma.ch = dma_request_slave_channel(dev, "rx");
-	if (!sdd->rx_dma.ch) {
-		dev_err(dev, "Failed to get RX DMA channel\n");
-		return -EBUSY;
-	}
 	spi->dma_rx = sdd->rx_dma.ch;
-
-	sdd->tx_dma.ch = dma_request_slave_channel(dev, "tx");
-	if (!sdd->tx_dma.ch) {
-		dev_err(dev, "Failed to get TX DMA channel\n");
-		dma_release_channel(sdd->rx_dma.ch);
-		return -EBUSY;
-	}
 	spi->dma_tx = sdd->tx_dma.ch;
 
 	return 0;
 }
 
-static int s3c64xx_spi_unprepare_transfer(struct spi_master *spi)
-{
-	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi);
-
-	/* Free DMA channels */
-	if (!is_polling(sdd)) {
-		dma_release_channel(sdd->rx_dma.ch);
-		dma_release_channel(sdd->tx_dma.ch);
-	}
-
-	return 0;
-}
-
 static bool s3c64xx_spi_can_dma(struct spi_master *master,
 				struct spi_device *spi,
 				struct spi_transfer *xfer)
@@ -1094,7 +1067,6 @@  static int s3c64xx_spi_probe(struct platform_device *pdev)
 	master->prepare_transfer_hardware = s3c64xx_spi_prepare_transfer;
 	master->prepare_message = s3c64xx_spi_prepare_message;
 	master->transfer_one = s3c64xx_spi_transfer_one;
-	master->unprepare_transfer_hardware = s3c64xx_spi_unprepare_transfer;
 	master->num_chipselect = sci->num_cs;
 	master->dma_alignment = 8;
 	master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(16) |
@@ -1161,6 +1133,24 @@  static int s3c64xx_spi_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (!is_polling(sdd)) {
+		/* Acquire DMA channels */
+		sdd->rx_dma.ch = dma_request_slave_channel_reason(&pdev->dev,
+								  "rx");
+		if (IS_ERR(sdd->rx_dma.ch)) {
+			dev_err(&pdev->dev, "Failed to get RX DMA channel\n");
+			ret = PTR_ERR(sdd->rx_dma.ch);
+			goto err_disable_io_clk;
+		}
+		sdd->tx_dma.ch = dma_request_slave_channel_reason(&pdev->dev,
+								  "tx");
+		if (IS_ERR(sdd->tx_dma.ch)) {
+			dev_err(&pdev->dev, "Failed to get TX DMA channel\n");
+			ret = PTR_ERR(sdd->tx_dma.ch);
+			goto err_release_tx_dma;
+		}
+	}
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev, AUTOSUSPEND_TIMEOUT);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);
@@ -1206,6 +1196,12 @@  static int s3c64xx_spi_probe(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_set_suspended(&pdev->dev);
 
+	if (!is_polling(sdd))
+		dma_release_channel(sdd->rx_dma.ch);
+err_release_tx_dma:
+	if (!is_polling(sdd))
+		dma_release_channel(sdd->tx_dma.ch);
+err_disable_io_clk:
 	clk_disable_unprepare(sdd->ioclk);
 err_disable_src_clk:
 	clk_disable_unprepare(sdd->src_clk);
@@ -1226,6 +1222,11 @@  static int s3c64xx_spi_remove(struct platform_device *pdev)
 
 	writel(0, sdd->regs + S3C64XX_SPI_INT_EN);
 
+	if (!is_polling(sdd)) {
+		dma_release_channel(sdd->rx_dma.ch);
+		dma_release_channel(sdd->tx_dma.ch);
+	}
+
 	clk_disable_unprepare(sdd->ioclk);
 
 	clk_disable_unprepare(sdd->src_clk);