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| author | Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com> | 2011-09-06 17:16:38 +0900 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2011-10-04 10:10:50 -0600 |
| commit | f3e03e2eb0bcd9266720695b82a523e6bc526ff7 (patch) | |
| tree | 12184b7ed8bea50f0ca10ff44c7f37e5c1bb0e07 /drivers/spi | |
| parent | 25e803f9c339a070cd7361e853aebde11b1f9217 (diff) | |
| download | linux-f3e03e2eb0bcd9266720695b82a523e6bc526ff7.tar.bz2 | |
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>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-topcliff-pch.c | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/drivers/spi/spi-topcliff-pch.c b/drivers/spi/spi-topcliff-pch.c index c8efa757fdaa..6a80749391db 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 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw) /* 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 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw) /* 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 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw) 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 */ |