| Message ID | 20200305191925.959494-6-seanga2@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | riscv: Add SPI support for Kendryte K210 | expand |
On 3/5/20 8:19 PM, Sean Anderson wrote: > 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 at gmail.com> > --- > > 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++; This breaks 16 bits per word transfers, NAK. The compiler should be able to figure out the rest of the optimizations in this patch.
On 3/21/20 9:49 PM, Marek Vasut wrote: > On 3/5/20 8:19 PM, Sean Anderson wrote: >> 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 at gmail.com> >> --- >> >> 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++; > > This breaks 16 bits per word transfers, NAK. > > The compiler should be able to figure out the rest of the optimizations > in this patch. > Hm, I will try with just the debug symbols removed. --Sean
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++; } }
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 at gmail.com> --- drivers/spi/designware_spi.c | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-)