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spi/xilinx: Use polling mode on small transfers

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Small transfers generally can be accomplished faster in polling mode.
This patch select the transfer which size is bellow the buffer size to
be done on polling mode

Suggested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Ricardo Ribalda Delgado 2015-01-28 13:23:54 +01:00 committed by Mark Brown
parent b563bfb8d7
commit 22417352f6
1 changed files with 25 additions and 18 deletions
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43
drivers/spi/spi-xilinx.c
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@ -128,7 +128,6 @@ static void xilinx_spi_rx(struct xilinx_spi *xspi)
static void xspi_init_hw(struct xilinx_spi *xspi)
{
void __iomem *regs_base = xspi->regs;
u32 inhibit;
/* Reset the SPI device */
xspi->write_fn(XIPIF_V123B_RESET_MASK,
@ -138,22 +137,15 @@ static void xspi_init_hw(struct xilinx_spi *xspi)
*/
xspi->write_fn(XSPI_INTR_TX_EMPTY,
regs_base + XIPIF_V123B_IIER_OFFSET);
/* Enable the global IPIF interrupt */
if (xspi->irq >= 0) {
xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
regs_base + XIPIF_V123B_DGIER_OFFSET);
inhibit = XSPI_CR_TRANS_INHIBIT;
} else {
xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
inhibit = 0;
}
/* Disable the global IPIF interrupt */
xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
/* Deselect the slave on the SPI bus */
xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
/* Disable the transmitter, enable Manual Slave Select Assertion,
* put SPI controller into master mode, and enable it */
xspi->write_fn(inhibit | XSPI_CR_MANUAL_SSELECT |
XSPI_CR_MASTER_MODE | XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET |
XSPI_CR_RXFIFO_RESET, regs_base + XSPI_CR_OFFSET);
xspi->write_fn(XSPI_CR_MANUAL_SSELECT | XSPI_CR_MASTER_MODE |
XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET | XSPI_CR_RXFIFO_RESET,
regs_base + XSPI_CR_OFFSET);
}
static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
@ -212,6 +204,8 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
int remaining_words; /* the number of words left to transfer */
bool use_irq = false;
u16 cr = 0;
/* We get here with transmitter inhibited */
@ -220,8 +214,20 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
remaining_words = t->len / xspi->bytes_per_word;
reinit_completion(&xspi->done);
if (xspi->irq >= 0 && remaining_words > xspi->buffer_size) {
use_irq = true;
xspi->write_fn(XSPI_INTR_TX_EMPTY,
xspi->regs + XIPIF_V123B_IISR_OFFSET);
/* Enable the global IPIF interrupt */
xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
xspi->regs + XIPIF_V123B_DGIER_OFFSET);
/* Inhibit irq to avoid spurious irqs on tx_empty*/
cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
xspi->regs + XSPI_CR_OFFSET);
}
while (remaining_words) {
u16 cr = 0;
int n_words, tx_words, rx_words;
n_words = min(remaining_words, xspi->buffer_size);
@ -234,9 +240,7 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
* longer
*/
if (xspi->irq >= 0) {
cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) &
~XSPI_CR_TRANS_INHIBIT;
if (use_irq) {
xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
wait_for_completion(&xspi->done);
} else
@ -249,7 +253,7 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
* transmitter while the Isr refills the transmit register/FIFO,
* or make sure it is stopped if we're done.
*/
if (xspi->irq >= 0)
if (use_irq)
xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
xspi->regs + XSPI_CR_OFFSET);
@ -261,6 +265,9 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
remaining_words -= n_words;
}
if (use_irq)
xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET);
return t->len;
}