Re: FAILED: patch "[PATCH] iio: stx104: Unregister IIO device on remove callback" failed to apply to 4.7-stable tree

[William Breathitt Gray <vilhelm.gray@gmail.com>]

On Thu, Sep 22, 2016 at 03:10:21PM +0200, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 4.7-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

This patch fixes an issues introduced in commit 765550e4d98d
("iio: stx104: Add GPIO support for the Apex Embedded Systems STX104").
If I'm not mistaken, commit 765550e4d98d is not in the 4.7-stable tree.
Since the source of the issue is not present, this patch to resolve the
issue should not be merged into 4.7-stable.

Sincerely,

William Breathitt Gray

>------------------ original commit in Linus's tree ------------------
>
>>From 45e98152850c36560484f3fa3bb857a4bfe1a419 Mon Sep 17 00:00:00 2001
>From: William Breathitt Gray <vilhelm.gray@gmail.com>
>Date: Tue, 19 Jul 2016 12:25:00 -0400
>Subject: [PATCH] iio: stx104: Unregister IIO device on remove callback
>
>The devm_iio_device_register function should not be used if custom
>operations must be performed in the remove callback. This patch replaces
>the dem_iio_device_register call with a iio_device_register call and
>respective iio_device_unregister call in the remove callback.
>
>Fixes: 765550e4d98d ("iio: stx104: Add GPIO support for the Apex Embedded Systems STX104")
>Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
>Cc: <Stable@vger.kernel.org>
>Signed-off-by: Jonathan Cameron <jic23@kernel.org>
>
>diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
>index 792a97164cb2..bebbd00304ce 100644
>--- a/drivers/iio/dac/stx104.c
>+++ b/drivers/iio/dac/stx104.c
>@@ -65,6 +65,16 @@ struct stx104_gpio {
> 	unsigned int out_state;
> };
> 
>+/**
>+ * struct stx104_dev - STX104 device private data structure
>+ * @indio_dev:	IIO device
>+ * @chip:	instance of the gpio_chip
>+ */
>+struct stx104_dev {
>+	struct iio_dev *indio_dev;
>+	struct gpio_chip *chip;
>+};
>+
> static int stx104_read_raw(struct iio_dev *indio_dev,
> 	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
> {
>@@ -107,6 +117,7 @@ static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
> static int stx104_gpio_get_direction(struct gpio_chip *chip,
> 	unsigned int offset)
> {
>+	/* GPIO 0-3 are input only, while the rest are output only */
> 	if (offset < 4)
> 		return 1;
> 
>@@ -169,6 +180,7 @@ static int stx104_probe(struct device *dev, unsigned int id)
> 	struct iio_dev *indio_dev;
> 	struct stx104_iio *priv;
> 	struct stx104_gpio *stx104gpio;
>+	struct stx104_dev *stx104dev;
> 	int err;
> 
> 	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
>@@ -179,6 +191,10 @@ static int stx104_probe(struct device *dev, unsigned int id)
> 	if (!stx104gpio)
> 		return -ENOMEM;
> 
>+	stx104dev = devm_kzalloc(dev, sizeof(*stx104dev), GFP_KERNEL);
>+	if (!stx104dev)
>+		return -ENOMEM;
>+
> 	if (!devm_request_region(dev, base[id], STX104_EXTENT,
> 		dev_name(dev))) {
> 		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
>@@ -199,12 +215,6 @@ static int stx104_probe(struct device *dev, unsigned int id)
> 	outw(0, base[id] + 4);
> 	outw(0, base[id] + 6);
> 
>-	err = devm_iio_device_register(dev, indio_dev);
>-	if (err) {
>-		dev_err(dev, "IIO device registering failed (%d)\n", err);
>-		return err;
>-	}
>-
> 	stx104gpio->chip.label = dev_name(dev);
> 	stx104gpio->chip.parent = dev;
> 	stx104gpio->chip.owner = THIS_MODULE;
>@@ -220,7 +230,9 @@ static int stx104_probe(struct device *dev, unsigned int id)
> 
> 	spin_lock_init(&stx104gpio->lock);
> 
>-	dev_set_drvdata(dev, stx104gpio);
>+	stx104dev->indio_dev = indio_dev;
>+	stx104dev->chip = &stx104gpio->chip;
>+	dev_set_drvdata(dev, stx104dev);
> 
> 	err = gpiochip_add_data(&stx104gpio->chip, stx104gpio);
> 	if (err) {
>@@ -228,14 +240,22 @@ static int stx104_probe(struct device *dev, unsigned int id)
> 		return err;
> 	}
> 
>+	err = iio_device_register(indio_dev);
>+	if (err) {
>+		dev_err(dev, "IIO device registering failed (%d)\n", err);
>+		gpiochip_remove(&stx104gpio->chip);
>+		return err;
>+	}
>+
> 	return 0;
> }
> 
> static int stx104_remove(struct device *dev, unsigned int id)
> {
>-	struct stx104_gpio *const stx104gpio = dev_get_drvdata(dev);
>+	struct stx104_dev *const stx104dev = dev_get_drvdata(dev);
> 
>-	gpiochip_remove(&stx104gpio->chip);
>+	iio_device_unregister(stx104dev->indio_dev);
>+	gpiochip_remove(stx104dev->chip);
> 
> 	return 0;
> }
>