It's possible for a SPI transaction to complete and get another
interrupt and have it processed on the same spi_transfer before the
transfer_one can set it to NULL.

This masks unexpected interrupts, so let's set the spi_transfer to
NULL in the interrupt once the transaction is done. So we can
properly detect these bad interrupts and print warning messages.

Signed-off-by: Matthew McClintock <mmccl...@codeaurora.org>
Signed-off-by: Varadarajan Narayanan <var...@codeaurora.org>
---
 drivers/spi/spi-qup.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index bd53e82..1a2a9d9 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
        struct spi_qup *controller = dev_id;
        struct spi_transfer *xfer;
        u32 opflags, qup_err, spi_err;
-       unsigned long flags;
        int error = 0;
+       bool done = 0;
 
-       spin_lock_irqsave(&controller->lock, flags);
+       spin_lock(&controller->lock);
        xfer = controller->xfer;
        controller->xfer = NULL;
-       spin_unlock_irqrestore(&controller->lock, flags);
+       spin_unlock(&controller->lock);
 
        qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
        spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);
@@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
                        spi_qup_write(controller, xfer);
        }
 
-       spin_lock_irqsave(&controller->lock, flags);
-       controller->error = error;
-       controller->xfer = xfer;
-       spin_unlock_irqrestore(&controller->lock, flags);
-
        /* re-read opflags as flags may have changed due to actions above */
        opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
 
        if ((controller->rx_bytes == xfer->len &&
                (opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
+               done = true;
+
+       spin_lock(&controller->lock);
+       controller->error = error;
+       controller->xfer = done ? NULL : xfer;
+       spin_unlock(&controller->lock);
+
+       if (done)
                complete(&controller->done);
 
        return IRQ_HANDLED;
@@ -765,7 +768,6 @@ static int spi_qup_transfer_one(struct spi_master *master,
 exit:
        spi_qup_set_state(controller, QUP_STATE_RESET);
        spin_lock_irqsave(&controller->lock, flags);
-       controller->xfer = NULL;
        if (!ret)
                ret = controller->error;
        spin_unlock_irqrestore(&controller->lock, flags);
-- 
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