spi/xilinx: Use polling mode on small transfers
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>
diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index 026f4c5..337fda4 100644
--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -128,7 +128,6 @@
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 @@
*/
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 @@
{
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 @@
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 @@
* 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 @@
* 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 @@
remaining_words -= n_words;
}
+ if (use_irq)
+ xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET);
+
return t->len;
}