openwrt_lede/target/linux/ipq806x/patches-4.4/714-spi-qup-properly-detect-extra-interrupts.patch

From b69e5e855aaae2dd9f7fc6f4a40af8e6e0cf98ee Mon Sep 17 00:00:00 2001
From: Matthew McClintock <mmcclint@codeaurora.org>
Date: Thu, 10 Mar 2016 16:44:55 -0600
Subject: [PATCH] spi: qup: properly detect extra interrupts

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.

Change-Id: I0e70ed59fb50e5c48a72a38f74bd178b17c9f24d
Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
---
 drivers/spi/spi-qup.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -509,6 +509,7 @@ static irqreturn_t spi_qup_qup_irq(int i
 	u32 opflags, qup_err, spi_err;
 	unsigned long flags;
 	int error = 0;
+	bool done = 0;
 
 	spin_lock_irqsave(&controller->lock, flags);
 	xfer = controller->xfer;
@@ -567,16 +568,19 @@ static irqreturn_t spi_qup_qup_irq(int i
 			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_irqsave(&controller->lock, flags);
+	controller->error = error;
+	controller->xfer = done ? NULL : xfer;
+	spin_unlock_irqrestore(&controller->lock, flags);
+
+	if (done)
 		complete(&controller->done);
 
 	return IRQ_HANDLED;
@@ -769,7 +773,6 @@ static int spi_qup_transfer_one(struct s
 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);