diff mbox

[6/6] spi: spi-s3c64xx: Allow higher transfer lengths in polling IO mode

Message ID 20180416154021.25626-6-s.nawrocki@samsung.com (mailing list archive)
State Not Applicable
Headers show

Commit Message

Sylwester Nawrocki/Kernel \(PLT\) /SRPOL/Staff Engineer/Samsung Electronics April 16, 2018, 3:40 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 | 108 ++++++++++++++++++++++++++++++----------------
 1 file changed, 71 insertions(+), 37 deletions(-)

Comments

Andi Shyti April 16, 2018, 7:19 p.m. UTC | #1 
Hi Sylwester,

On 17.04.2018 00:40, 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.

this patch is a mix of cosmetics and what you are actually describing
in the commit log...

> @@ -634,11 +634,15 @@ static int s3c64xx_spi_transfer_one(struct
> spi_master *master,
>  				    struct spi_transfer *xfer)
>  {
>  	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;
> +	bool use_dma = false;
>  	int status;
>  	u32 speed;
>  	u8 bpw;
>  	unsigned long flags;
> -	int use_dma;

... for example 'use_dma' bool instead of int or the 'fifo_len'. I agree
with these changes and, even though they are trivial, I would prefer
having them in separate patches.

Thanks,
Andi
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Sylwester Nawrocki/Kernel \(PLT\) /SRPOL/Staff Engineer/Samsung Electronics April 17, 2018, 9:07 a.m. UTC | #2 
Hi Andi,

On 04/16/2018 09:19 PM, andi@etezian.org wrote:
> On 17.04.2018 00:40, 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.
> 
> this patch is a mix of cosmetics and what you are actually describing
> in the commit log...
> 
>> @@ -634,11 +634,15 @@ static int s3c64xx_spi_transfer_one(struct
>> spi_master *master,
>>  				    struct spi_transfer *xfer)
>>  {
>>  	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;
>> +	bool use_dma = false;
>>  	int status;
>>  	u32 speed;
>>  	u8 bpw;
>>  	unsigned long flags;
>> -	int use_dma;
> 
> ... for example 'use_dma' bool instead of int or the 'fifo_len'. I agree
> with these changes and, even though they are trivial, I would prefer
> having them in separate patches.

Thanks for your review! I will split that into 3 patches then, however
it seems a bit dubious to have the fifo_len change on its own.
diff mbox

Patch

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 2723fa6bed8b..b2e8ed354dac 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -349,7 +349,7 @@  static bool s3c64xx_spi_can_dma(struct spi_master *master,
 }
 
 static void s3c64xx_enable_datapath(struct s3c64xx_spi_driver_data *sdd,
-				    struct spi_transfer *xfer, int dma_mode)
+				    struct spi_transfer *xfer, bool dma_mode)
 {
 	void __iomem *regs = sdd->regs;
 	u32 modecfg, chcfg;
@@ -634,11 +634,15 @@  static int s3c64xx_spi_transfer_one(struct spi_master *master,
 				    struct spi_transfer *xfer)
 {
 	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;
+	bool use_dma = false;
 	int status;
 	u32 speed;
 	u8 bpw;
 	unsigned long flags;
-	int use_dma;
 
 	reinit_completion(&sdd->xfer_completion);
 
@@ -653,48 +657,78 @@  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) &&
-	    (sdd->rx_dma.ch && sdd->tx_dma.ch &&
-	     (xfer->len > ((FIFO_LVL_MASK(sdd) >> 1) + 1))))
-		use_dma = 1;
+	if (!is_polling(sdd) && (xfer->len > fifo_len) &&
+	    sdd->rx_dma.ch && sdd->tx_dma.ch) {
+		use_dma = true;
 
-	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 = wait_for_dma(sdd, xfer);
-	else
-		status = 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 = wait_for_dma(sdd, xfer);
+		else
+			status = 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 {
+			flush_fifo(sdd);
 		}
-	} else {
-		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;