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: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/spi/spi-topcliff-pch.c b/drivers/spi/spi-topcliff-pch.c
index c8efa75..6a80749 100644
--- a/drivers/spi/spi-topcliff-pch.c
+++ b/drivers/spi/spi-topcliff-pch.c
@@ -50,6 +50,8 @@
#define PCH_RX_THOLD 7
#define PCH_RX_THOLD_MAX 15
+#define PCH_TX_THOLD 2
+
#define PCH_MAX_BAUDRATE 5000000
#define PCH_MAX_FIFO_DEPTH 16
@@ -1040,8 +1042,7 @@
/* set receive fifo threshold and transmit fifo threshold */
pch_spi_setclr_reg(data->master, PCH_SPCR,
((size - 1) << SPCR_RFIC_FIELD) |
- ((PCH_MAX_FIFO_DEPTH - PCH_DMA_TRANS_SIZE) <<
- SPCR_TFIC_FIELD),
+ (PCH_TX_THOLD << SPCR_TFIC_FIELD),
MASK_RFIC_SPCR_BITS | MASK_TFIC_SPCR_BITS);
spin_unlock_irqrestore(&data->lock, flags);
@@ -1052,13 +1053,20 @@
/* offset, length setting */
sg = dma->sg_rx_p;
for (i = 0; i < num; i++, sg++) {
- if (i == 0) {
- sg->offset = 0;
+ if (i == (num - 2)) {
+ sg->offset = size * i;
+ sg->offset = sg->offset * (*bpw / 8);
sg_set_page(sg, virt_to_page(dma->rx_buf_virt), rem,
sg->offset);
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 {
- sg->offset = rem + size * (i - 1);
+ sg->offset = size * i;
sg->offset = sg->offset * (*bpw / 8);
sg_set_page(sg, virt_to_page(dma->rx_buf_virt), size,
sg->offset);
@@ -1082,6 +1090,16 @@
dma->desc_rx = desc_rx;
/* 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);
sg_init_table(dma->sg_tx_p, num); /* Initialize SG table */
/* offset, length setting */