[PATCH 4.2 099/120] spi/spi-xilinx: Fix spurious IRQ ACK on irq mode

Greg Kroah-Hartman
2015-09-19T17:51:34Z

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

commit 74346841e6f5df5f7b83d5904435d273c507dba6 upstream.

The ACK of an inexistent IRQ can trigger an spurious IRQ that breaks the
txrx logic. This has been observed on axi_quad_spi:3.2 core.

This patch only ACKs IRQs that have not been Acknowledge jet.

Reported-by: Edward Kigwana <ekigwana@scires.com>
Tested-by: Edward Kigwana <ekigwana@scires.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/spi/spi-xilinx.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -249,19 +249,23 @@ static int xilinx_spi_txrx_bufs(struct s
xspi->tx_ptr = t->tx_buf;
xspi->rx_ptr = t->rx_buf;
remaining_words = t->len / xspi->bytes_per_word;
- reinit_completion(&xspi->done);

if (xspi->irq >= 0 && remaining_words > xspi->buffer_size) {
+ u32 isr;
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);
+ /* ACK old irqs (if any) */
+ isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
+ if (isr)
+ xspi->write_fn(isr,
+ xspi->regs + XIPIF_V123B_IISR_OFFSET);
+ /* Enable the global IPIF interrupt */
+ xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
+ xspi->regs + XIPIF_V123B_DGIER_OFFSET);
+ reinit_completion(&xspi->done);
}

while (remaining_words) {