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Commit f3e03e2e authored by Tomoya MORINAGA's avatar Tomoya MORINAGA Committed by Grant Likely
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spi-topcliff-pch: Fix overrun issue 



We found that adding load, Rx data sometimes drops.(with DMA transfer mode)
The cause is that before starting Rx-DMA processing, Tx-DMA processing starts.
This causes FIFO overrun occurs.

This patch fixes the issue by modifying FIFO tx-threshold and DMA descriptor
size like below.

                      Current                   this patch
Rx-descriptor   4Byte+12Byte*341    -->    12Byte*340-4Byte-12Byte
Rx-threshold                   (Not modified)
Tx-descriptor   4Byte+12Byte*341    -->    16Byte-12Byte*340
Rx-threshold    12Byte              -->    2Byte

Signed-off-by: default avatarTomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 25e803f9

drivers/spi/spi-topcliff-pch.c

+23 −5
Original line number Original line Diff line number Diff line
@@ -50,6 +50,8 @@ 
#define PCH_RX_THOLD		7

#define PCH_RX_THOLD		7

#define PCH_RX_THOLD_MAX	15

#define PCH_RX_THOLD_MAX	15





#define PCH_TX_THOLD		2



#define PCH_MAX_BAUDRATE	5000000

#define PCH_MAX_BAUDRATE	5000000

#define PCH_MAX_FIFO_DEPTH	16

#define PCH_MAX_FIFO_DEPTH	16
@@ -1040,8 +1042,7 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw) 
	/* set receive fifo threshold and transmit fifo threshold */

	/* set receive fifo threshold and transmit fifo threshold */

	pch_spi_setclr_reg(data->master, PCH_SPCR,

	pch_spi_setclr_reg(data->master, PCH_SPCR,

			   ((size - 1) << SPCR_RFIC_FIELD) |

			   ((size - 1) << SPCR_RFIC_FIELD) |

			   ((PCH_MAX_FIFO_DEPTH - PCH_DMA_TRANS_SIZE) <<

			   (PCH_TX_THOLD << SPCR_TFIC_FIELD),

			    SPCR_TFIC_FIELD),

			   MASK_RFIC_SPCR_BITS | MASK_TFIC_SPCR_BITS);

			   MASK_RFIC_SPCR_BITS | MASK_TFIC_SPCR_BITS);





	spin_unlock_irqrestore(&data->lock, flags);

	spin_unlock_irqrestore(&data->lock, flags);
@@ -1052,13 +1053,20 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw) 
	/* offset, length setting */

	/* offset, length setting */

	sg = dma->sg_rx_p;

	sg = dma->sg_rx_p;

	for (i = 0; i < num; i++, sg++) {

	for (i = 0; i < num; i++, sg++) {

		if (i == 0) {

		if (i == (num - 2)) {

			sg->offset = 0;

			sg->offset = size * i;

			sg->offset = sg->offset * (*bpw / 8);

			sg_set_page(sg, virt_to_page(dma->rx_buf_virt), rem,

			sg_set_page(sg, virt_to_page(dma->rx_buf_virt), rem,

				    sg->offset);

				    sg->offset);

			sg_dma_len(sg) = rem;

			sg_dma_len(sg) = rem;

		} else if (i == (num - 1)) {

			sg->offset = size * (i - 1) + rem;

			sg->offset = sg->offset * (*bpw / 8);

			sg_set_page(sg, virt_to_page(dma->rx_buf_virt), size,

				    sg->offset);

			sg_dma_len(sg) = size;

		} else {

		} else {

			sg->offset = rem + size * (i - 1);

			sg->offset = size * i;

			sg->offset = sg->offset * (*bpw / 8);

			sg->offset = sg->offset * (*bpw / 8);

			sg_set_page(sg, virt_to_page(dma->rx_buf_virt), size,

			sg_set_page(sg, virt_to_page(dma->rx_buf_virt), size,

				    sg->offset);

				    sg->offset);
@@ -1082,6 +1090,16 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw) 
	dma->desc_rx = desc_rx;

	dma->desc_rx = desc_rx;





	/* TX */

	/* TX */

	if (data->bpw_len > PCH_DMA_TRANS_SIZE) {

		num = data->bpw_len / PCH_DMA_TRANS_SIZE;

		size = PCH_DMA_TRANS_SIZE;

		rem = 16;

	} else {

		num = 1;

		size = data->bpw_len;

		rem = data->bpw_len;

	}



	dma->sg_tx_p = kzalloc(sizeof(struct scatterlist)*num, GFP_ATOMIC);

	dma->sg_tx_p = kzalloc(sizeof(struct scatterlist)*num, GFP_ATOMIC);

	sg_init_table(dma->sg_tx_p, num); /* Initialize SG table */

	sg_init_table(dma->sg_tx_p, num); /* Initialize SG table */

	/* offset, length setting */

	/* offset, length setting */