diff mbox

[v2,8/8] spi: spi-s3c64xx: Allow higher transfer lengths in polling IO mode

Message ID 20180417142954.5507-8-s.nawrocki@samsung.com (mailing list archive)
State Not Applicable
Headers show

Commit Message

Sylwester Nawrocki/Kernel \(PLT\) /SRPOL/Staff Engineer/Samsung Electronics April 17, 2018, 2:29 p.m. UTC 
Some variants of the SPI controller have no DMA support, in such case
SPI transfers longer than the FIFO length are not currently properly
handled by the driver. Fix it by doing multiple transfers in the
s3c64xx_spi_transfer_one() function if the SPI transfer length exceeds
the FIFO size.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
---
 drivers/spi/spi-s3c64xx.c | 99 +++++++++++++++++++++++++++++++----------------
 1 file changed, 66 insertions(+), 33 deletions(-)

Comments

Andi Shyti April 17, 2018, 6:27 p.m. UTC | #1 
Hi Sylwester,

On 17.04.2018 23:29, Sylwester Nawrocki wrote:
> Some variants of the SPI controller have no DMA support, in such case
> SPI transfers longer than the FIFO length are not currently properly
> handled by the driver. Fix it by doing multiple transfers in the
> s3c64xx_spi_transfer_one() function if the SPI transfer length exceeds
> the FIFO size.
> 
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

thank you! it looks good.

Unfortunately I don't have right now the device with me
to test it, in any case you can add

Reviewed-by: Andi Shyti <andi@etezian.org>

Thanks,
Andi
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diff mbox

Patch

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 27cd8c59eabf..755ab2dc6969 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -635,11 +635,14 @@  static int s3c64xx_spi_transfer_one(struct spi_master *master,
 {
 	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
 	const unsigned int fifo_len = (FIFO_LVL_MASK(sdd) >> 1) + 1;
+	const void *tx_buf = NULL;
+	void *rx_buf = NULL;
+	int target_len = 0, origin_len = 0;
+	int use_dma = 0;
 	int status;
 	u32 speed;
 	u8 bpw;
 	unsigned long flags;
-	int use_dma;
 
 	reinit_completion(&sdd->xfer_completion);
 
@@ -654,47 +657,77 @@  static int s3c64xx_spi_transfer_one(struct spi_master *master,
 		s3c64xx_spi_config(sdd);
 	}
 
-	/* Polling method for xfers not bigger than FIFO capacity */
-	use_dma = 0;
 	if (!is_polling(sdd) && (xfer->len > fifo_len) &&
-	    sdd->rx_dma.ch && sdd->tx_dma.ch)
+	    sdd->rx_dma.ch && sdd->tx_dma.ch) {
 		use_dma = 1;
 
-	spin_lock_irqsave(&sdd->lock, flags);
+	} else if (is_polling(sdd) && xfer->len > fifo_len) {
+		tx_buf = xfer->tx_buf;
+		rx_buf = xfer->rx_buf;
+		origin_len = xfer->len;
 
-	/* Pending only which is to be done */
-	sdd->state &= ~RXBUSY;
-	sdd->state &= ~TXBUSY;
+		target_len = xfer->len;
+		if (xfer->len > fifo_len)
+			xfer->len = fifo_len;
+	}
+
+	do {
+		spin_lock_irqsave(&sdd->lock, flags);
 
-	s3c64xx_enable_datapath(sdd, xfer, use_dma);
+		/* Pending only which is to be done */
+		sdd->state &= ~RXBUSY;
+		sdd->state &= ~TXBUSY;
 
-	/* Start the signals */
-	s3c64xx_spi_set_cs(spi, true);
+		s3c64xx_enable_datapath(sdd, xfer, use_dma);
 
-	spin_unlock_irqrestore(&sdd->lock, flags);
+		/* Start the signals */
+		s3c64xx_spi_set_cs(spi, true);
 
-	if (use_dma)
-		status = s3c64xx_wait_for_dma(sdd, xfer);
-	else
-		status = s3c64xx_wait_for_pio(sdd, xfer);
-
-	if (status) {
-		dev_err(&spi->dev, "I/O Error: rx-%d tx-%d res:rx-%c tx-%c len-%d\n",
-			xfer->rx_buf ? 1 : 0, xfer->tx_buf ? 1 : 0,
-			(sdd->state & RXBUSY) ? 'f' : 'p',
-			(sdd->state & TXBUSY) ? 'f' : 'p',
-			xfer->len);
-
-		if (use_dma) {
-			if (xfer->tx_buf != NULL
-			    && (sdd->state & TXBUSY))
-				dmaengine_terminate_all(sdd->tx_dma.ch);
-			if (xfer->rx_buf != NULL
-			    && (sdd->state & RXBUSY))
-				dmaengine_terminate_all(sdd->rx_dma.ch);
+		spin_unlock_irqrestore(&sdd->lock, flags);
+
+		if (use_dma)
+			status = s3c64xx_wait_for_dma(sdd, xfer);
+		else
+			status = s3c64xx_wait_for_pio(sdd, xfer);
+
+		if (status) {
+			dev_err(&spi->dev,
+				"I/O Error: rx-%d tx-%d res:rx-%c tx-%c len-%d\n",
+				xfer->rx_buf ? 1 : 0, xfer->tx_buf ? 1 : 0,
+				(sdd->state & RXBUSY) ? 'f' : 'p',
+				(sdd->state & TXBUSY) ? 'f' : 'p',
+				xfer->len);
+
+			if (use_dma) {
+				if (xfer->tx_buf && (sdd->state & TXBUSY))
+					dmaengine_terminate_all(sdd->tx_dma.ch);
+				if (xfer->rx_buf && (sdd->state & RXBUSY))
+					dmaengine_terminate_all(sdd->rx_dma.ch);
+			}
+		} else {
+			s3c64xx_flush_fifo(sdd);
 		}
-	} else {
-		s3c64xx_flush_fifo(sdd);
+		if (target_len > 0) {
+			target_len -= xfer->len;
+
+			if (xfer->tx_buf)
+				xfer->tx_buf += xfer->len;
+
+			if (xfer->rx_buf)
+				xfer->rx_buf += xfer->len;
+
+			if (target_len > fifo_len)
+				xfer->len = fifo_len;
+			else
+				xfer->len = target_len;
+		}
+	} while (target_len > 0);
+
+	if (origin_len) {
+		/* Restore original xfer buffers and length */
+		xfer->tx_buf = tx_buf;
+		xfer->rx_buf = rx_buf;
+		xfer->len = origin_len;
 	}
 
 	return status;