The transfer loops are very tight on some platforms (especially on higher speeds). If we don't read/write fast enough we can run into over-/under- flow problems. This patch removes several divisions and log statements, and simplifies the read logic.
Signed-off-by: Sean Anderson seanga2@gmail.com ---
Changes in v5: - New
drivers/spi/designware_spi.c | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-)
diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c index 38c24fe550..613eb0d0e6 100644 --- a/drivers/spi/designware_spi.c +++ b/drivers/spi/designware_spi.c @@ -304,7 +304,7 @@ static inline u32 tx_max(struct dw_spi_priv *priv) { u32 tx_left, tx_room, rxtx_gap;
- tx_left = (priv->tx_end - priv->tx) / (priv->bits_per_word >> 3); + tx_left = priv->tx_end - priv->tx; tx_room = priv->fifo_len - dw_read(priv, DW_SPI_TXFLR);
/* @@ -315,8 +315,7 @@ static inline u32 tx_max(struct dw_spi_priv *priv) * shift registers. So a control from sw point of * view is taken. */ - rxtx_gap = ((priv->rx_end - priv->rx) - (priv->tx_end - priv->tx)) / - (priv->bits_per_word >> 3); + rxtx_gap = ((priv->rx_end - priv->rx) - (priv->tx_end - priv->tx));
return min3(tx_left, tx_room, (u32)(priv->fifo_len - rxtx_gap)); } @@ -324,7 +323,7 @@ static inline u32 tx_max(struct dw_spi_priv *priv) /* Return the max entries we should read out of rx fifo */ static inline u32 rx_max(struct dw_spi_priv *priv) { - u32 rx_left = (priv->rx_end - priv->rx) / (priv->bits_per_word >> 3); + u32 rx_left = priv->rx_end - priv->rx;
return min_t(u32, rx_left, dw_read(priv, DW_SPI_RXFLR)); } @@ -336,15 +335,10 @@ static void dw_writer(struct dw_spi_priv *priv)
while (max--) { /* Set the tx word if the transfer's original "tx" is not null */ - if (priv->tx_end - priv->len) { - if (priv->bits_per_word == 8) - txw = *(u8 *)(priv->tx); - else - txw = *(u16 *)(priv->tx); - } + if (priv->tx_end - priv->len) + txw = *(u8 *)(priv->tx); dw_write(priv, DW_SPI_DR, txw); - debug("%s: tx=0x%02x\n", __func__, txw); - priv->tx += priv->bits_per_word >> 3; + priv->tx++; } }
@@ -355,16 +349,11 @@ static void dw_reader(struct dw_spi_priv *priv)
while (max--) { rxw = dw_read(priv, DW_SPI_DR); - debug("%s: rx=0x%02x\n", __func__, rxw);
/* Care about rx if the transfer's original "rx" is not null */ - if (priv->rx_end - priv->len) { - if (priv->bits_per_word == 8) - *(u8 *)(priv->rx) = rxw; - else - *(u16 *)(priv->rx) = rxw; - } - priv->rx += priv->bits_per_word >> 3; + if (priv->rx_end - priv->len) + *(u8 *)(priv->rx) = rxw; + priv->rx++; } }