spi/spi-xilinx: Fix spurious IRQ ACK on irq mode

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>
Cc: stable@vger.kernel.org

1 files changed, 10 insertions, 6 deletions

diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index 7abf6792cc11..a339c1e9997a 100644
--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -249,19 +249,23 @@ static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
         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) {