[PATCH for-4.14.y 2/3] i2c: qup: fixed releasing dma without flush operation completion

[Amit Pundir <amit.pundir@linaro.org>]

From: Abhishek Sahu <absahu@codeaurora.org>

commit 7239872fb3400b21a8f5547257f9f86455867bd6 upstream.

The QUP BSLP BAM generates the following error sometimes if the
current I2C DMA transfer fails and the flush operation has been
scheduled

    “bam-dma-engine 7884000.dma: Cannot free busy channel”

If any I2C error comes during BAM DMA transfer, then the QUP I2C
interrupt will be generated and the flush operation will be
carried out to make I2C consume all scheduled DMA transfer.
Currently, the same completion structure is being used for BAM
transfer which has already completed without reinit. It will make
flush operation wait_for_completion_timeout completed immediately
and will proceed for freeing the DMA resources where the
descriptors are still in process.

Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
Acked-by: Sricharan R <sricharan@codeaurora.org>
Reviewed-by: Austin Christ <austinwc@codeaurora.org>
Reviewed-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
---
Cherry-picked from lede/openwrt tree
https://git.lede-project.org/?p=source.git.
Build tested for ARCH=arm64 + defconfig

It is part of a clean-up series but it holds
good on it's own as well. I think.
https://patchwork.ozlabs.org/cover/868855/

Cleanly apply on 4.9.y as well but since
lede stopped supporting v4.9.y, I'm not
sure if this patch is tested on v4.9.y at all.

 drivers/i2c/busses/i2c-qup.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
index 08f8e0107642..8f6903ec7aec 100644
--- a/drivers/i2c/busses/i2c-qup.c
+++ b/drivers/i2c/busses/i2c-qup.c
@@ -844,6 +844,8 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
 	}
 
 	if (ret || qup->bus_err || qup->qup_err) {
+		reinit_completion(&qup->xfer);
+
 		if (qup_i2c_change_state(qup, QUP_RUN_STATE)) {
 			dev_err(qup->dev, "change to run state timed out");
 			goto desc_err;
-- 
2.7.4