FAILED: patch "[PATCH] spi: spi-fsl-dspi: Fix lockup if device is removed during SPI" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7684580d45bd3d84ed9b453a4cadf7a9a5605a3f Mon Sep 17 00:00:00 2001
From: Krzysztof Kozlowski <krzk@kernel.org>
Date: Mon, 22 Jun 2020 13:05:40 +0200
Subject: [PATCH] spi: spi-fsl-dspi: Fix lockup if device is removed during SPI
 transfer

During device removal, the driver should unregister the SPI controller
and stop the hardware.  Otherwise the dspi_transfer_one_message() could
wait on completion infinitely.

Additionally, calling spi_unregister_controller() first in device
removal reverse-matches the probe function, where SPI controller is
registered at the end.

Fixes: 05209f457069 ("spi: fsl-dspi: add missing clk_disable_unprepare() in dspi_remove()")
Reported-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200622110543.5035-1-krzk@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 58190c94561f..ec0fd0d366eb 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -1434,9 +1434,18 @@ static int dspi_remove(struct platform_device *pdev)
 	struct fsl_dspi *dspi = spi_controller_get_devdata(ctlr);
 
 	/* Disconnect from the SPI framework */
+	spi_unregister_controller(dspi->ctlr);
+
+	/* Disable RX and TX */
+	regmap_update_bits(dspi->regmap, SPI_MCR,
+			   SPI_MCR_DIS_TXF | SPI_MCR_DIS_RXF,
+			   SPI_MCR_DIS_TXF | SPI_MCR_DIS_RXF);
+
+	/* Stop Running */
+	regmap_update_bits(dspi->regmap, SPI_MCR, SPI_MCR_HALT, SPI_MCR_HALT);
+
 	dspi_release_dma(dspi);
 	clk_disable_unprepare(dspi->clk);
-	spi_unregister_controller(dspi->ctlr);
 
 	return 0;
 }