linux-kernel - [PATCH RFC v4 10/15] iio: buffer-dmaengine: document iio_dmaengine_buffer_setup

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Message-Id: <20241023-dlech-mainline-spi-engine-offload-2-v4-10-f8125b99f5a1@baylibre.com>
Date: Wed, 23 Oct 2024 15:59:17 -0500
From: David Lechner <dlechner@...libre.com>
To: Mark Brown <broonie@...nel.org>, Jonathan Cameron <jic23@...nel.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Uwe Kleine-König <ukleinek@...nel.org>
Cc: Michael Hennerich <Michael.Hennerich@...log.com>, 
 Lars-Peter Clausen <lars@...afoo.de>, David Jander <david@...tonic.nl>, 
 Martin Sperl <kernel@...tin.sperl.org>, linux-spi@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-iio@...r.kernel.org, linux-pwm@...r.kernel.org, 
 David Lechner <dlechner@...libre.com>
Subject: [PATCH RFC v4 10/15] iio: buffer-dmaengine: document
 iio_dmaengine_buffer_setup_ext

The iio_dmaengine_buffer_setup_ext() function is public and should be
documented. Also, while touching this, fix the description of @dev in
related functions. @dev does not strictly have to be the parent of the
IIO device. It is only passed to dma_request_chan() so strictly
speaking, it can be any device that is a valid DMA channel consumer.

Signed-off-by: David Lechner <dlechner@...libre.com>
---

v4 changes:
* This patch is new in v4.

Jonathan, I think this patch stands on its own if you want to take it
earlier than the rest of this series.
---
 drivers/iio/buffer/industrialio-buffer-dmaengine.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
index 19af1caf14cd..054af21dfa65 100644
--- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
+++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
@@ -206,7 +206,7 @@ static const struct iio_dev_attr *iio_dmaengine_buffer_attrs[] = {
 
 /**
  * iio_dmaengine_buffer_alloc() - Allocate new buffer which uses DMAengine
- * @dev: Parent device for the buffer
+ * @dev: DMA channel consumer device
  * @channel: DMA channel name, typically "rx".
  *
  * This allocates a new IIO buffer which internally uses the DMAengine framework
@@ -288,6 +288,21 @@ void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
 }
 EXPORT_SYMBOL_NS_GPL(iio_dmaengine_buffer_free, IIO_DMAENGINE_BUFFER);
 
+/**
+ * iio_dmaengine_buffer_setup_ext() - Setup a DMA buffer for an IIO device
+ * @dev: DMA channel consumer device
+ * @indio_dev: IIO device to which to attach this buffer.
+ * @channel: DMA channel name, typically "rx".
+ * @dir: Direction of buffer (in or out)
+ *
+ * This allocates a new IIO buffer with devm_iio_dmaengine_buffer_alloc()
+ * and attaches it to an IIO device with iio_device_attach_buffer().
+ * It also appends the INDIO_BUFFER_HARDWARE mode to the supported modes of the
+ * IIO device.
+ *
+ * Once done using the buffer iio_dmaengine_buffer_free() should be used to
+ * release it.
+ */
 struct iio_buffer *iio_dmaengine_buffer_setup_ext(struct device *dev,
 						  struct iio_dev *indio_dev,
 						  const char *channel,
@@ -321,7 +336,7 @@ static void __devm_iio_dmaengine_buffer_free(void *buffer)
 
 /**
  * devm_iio_dmaengine_buffer_setup_ext() - Setup a DMA buffer for an IIO device
- * @dev: Parent device for the buffer
+ * @dev: Device for devm ownership and DMA channel consumer device
  * @indio_dev: IIO device to which to attach this buffer.
  * @channel: DMA channel name, typically "rx".
  * @dir: Direction of buffer (in or out)

-- 
2.43.0