From patchwork Thu Mar 5 19:19:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Anderson X-Patchwork-Id: 243262 List-Id: U-Boot discussion From: seanga2 at gmail.com (Sean Anderson) Date: Thu, 5 Mar 2020 14:19:22 -0500 Subject: [PATCH v1 5/8] spi: dw: Speed up transfer loops In-Reply-To: <20200305191925.959494-1-seanga2@gmail.com> References: <20200305191925.959494-1-seanga2@gmail.com> Message-ID: <20200305191925.959494-6-seanga2@gmail.com> 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 --- 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++; } }