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authorPeter Crosthwaite <peter.crosthwaite@petalogix.com>2013-06-04 16:02:34 +0200
committerMark Brown <broonie@linaro.org>2013-06-04 18:32:19 +0100
commit68c315bb951d94210c43c52166d326f9c26f7ce8 (patch)
tree1708d43440a40b87ce0531941a91f09c8d30f507
parentd683b96b072dc4680fc74964eca77e6a23d1fa6e (diff)
spi: spi-xilinx: Remove ISR race condition
The ISR currently consumes the rx buffer data and re-enables transmission from within interrupt context. This is bad because if the interrupt occurs again before the ISR exits, the new interrupt will be erroneously cleared by the still completing ISR. Simplified the ISR by just setting the completion variable and exiting with no action. Then just looped the transmit functionality in xilinx_spi_txrx_bufs(). Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com> Signed-off-by: Michal Simek <michal.simek@xilinx.com> Signed-off-by: Mark Brown <broonie@linaro.org>
-rw-r--r--drivers/spi/spi-xilinx.c74
1 files changed, 35 insertions, 39 deletions
diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index e1d769607425..34d18dcfa0db 100644
--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -267,7 +267,6 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
u32 ipif_ier;
- u16 cr;
/* We get here with transmitter inhibited */
@@ -276,7 +275,6 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
xspi->remaining_bytes = t->len;
INIT_COMPLETION(xspi->done);
- xilinx_spi_fill_tx_fifo(xspi);
/* Enable the transmit empty interrupt, which we use to determine
* progress on the transmission.
@@ -285,12 +283,41 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
xspi->write_fn(ipif_ier | XSPI_INTR_TX_EMPTY,
xspi->regs + XIPIF_V123B_IIER_OFFSET);
- /* Start the transfer by not inhibiting the transmitter any longer */
- cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) &
- ~XSPI_CR_TRANS_INHIBIT;
- xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
+ for (;;) {
+ u16 cr;
+ u8 sr;
+
+ xilinx_spi_fill_tx_fifo(xspi);
+
+ /* Start the transfer by not inhibiting the transmitter any
+ * longer
+ */
+ cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) &
+ ~XSPI_CR_TRANS_INHIBIT;
+ xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
+
+ wait_for_completion(&xspi->done);
+
+ /* A transmit has just completed. Process received data and
+ * check for more data to transmit. Always inhibit the
+ * transmitter while the Isr refills the transmit register/FIFO,
+ * or make sure it is stopped if we're done.
+ */
+ cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
+ xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
+ xspi->regs + XSPI_CR_OFFSET);
+
+ /* Read out all the data from the Rx FIFO */
+ sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
+ while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
+ xspi->rx_fn(xspi);
+ sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
+ }
- wait_for_completion(&xspi->done);
+ /* See if there is more data to send */
+ if (!xspi->remaining_bytes > 0)
+ break;
+ }
/* Disable the transmit empty interrupt */
xspi->write_fn(ipif_ier, xspi->regs + XIPIF_V123B_IIER_OFFSET);
@@ -314,38 +341,7 @@ static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);
if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */
- u16 cr;
- u8 sr;
-
- /* A transmit has just completed. Process received data and
- * check for more data to transmit. Always inhibit the
- * transmitter while the Isr refills the transmit register/FIFO,
- * or make sure it is stopped if we're done.
- */
- cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
- xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
- xspi->regs + XSPI_CR_OFFSET);
-
- /* Read out all the data from the Rx FIFO */
- sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
- while ((sr & XSPI_SR_RX_EMPTY_MASK) == 0) {
- xspi->rx_fn(xspi);
- sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
- }
-
- /* See if there is more data to send */
- if (xspi->remaining_bytes > 0) {
- xilinx_spi_fill_tx_fifo(xspi);
- /* Start the transfer by not inhibiting the
- * transmitter any longer
- */
- xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
- } else {
- /* No more data to send.
- * Indicate the transfer is completed.
- */
- complete(&xspi->done);
- }
+ complete(&xspi->done);
}
return IRQ_HANDLED;