linux-kernel - [PATCH 1/2] spi: Add call to spi_slave_abort() function when spidev driver is released

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Message-Id: <20190924110547.14770-2-lukma@denx.de>
Date:   Tue, 24 Sep 2019 13:05:46 +0200
From:   Lukasz Majewski <lukma@...x.de>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        krzk@...nel.org, Lukasz Majewski <lukma@...x.de>
Subject: [PATCH 1/2] spi: Add call to spi_slave_abort() function when spidev driver is released

This change is necessary for spidev devices (e.g. /dev/spidev3.0) working
in the slave mode (like NXP's dspi driver for Vybrid SoC).

When SPI HW works in this mode - the master is responsible for providing
CS and CLK signals. However, when some fault happens - like for example
distortion on SPI lines - the SPI Linux driver needs a chance to recover
from this abnormal situation and prepare itself for next (correct)
transmission.

This change doesn't pose any threat on drivers working in master mode as
spi_slave_abort() function checks if SPI slave mode is supported.

Signed-off-by: Lukasz Majewski <lukma@...x.de>
---
 drivers/spi/spidev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 255786f2e844..fe9ea7e55e5b 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -627,6 +627,7 @@ static int spidev_release(struct inode *inode, struct file *filp)
 		if (dofree)
 			kfree(spidev);
 	}
+	spi_slave_abort(spidev->spi);
 	mutex_unlock(&device_list_lock);

 	return 0;
-- 
2.20.1