[PATCH v2 1/4] dma: Add devm_dma_request_chan()

[PATCH v2 1/4] dma: Add devm_dma_request_chan()

[Bence Csókás]

Expand the arsenal of devm functions for DMA
devices, this time for requesting channels.

Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
---
 drivers/dma/dmaengine.c   | 30 ++++++++++++++++++++++++++++++
 include/linux/dmaengine.h |  7 +++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index c1357d7f3dc6..02c29d26ac85 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -926,6 +926,36 @@ void dma_release_channel(struct dma_chan *chan)
 }
 EXPORT_SYMBOL_GPL(dma_release_channel);
 
+static void dmaenginem_release_channel(void *chan)
+{
+	dma_release_channel(chan);
+}
+
+/**
+ * devm_dma_request_chan - try to allocate an exclusive slave channel
+ * @dev:	pointer to client device structure
+ * @name:	slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
+ *
+ * The operation is managed and will be undone on driver detach.
+ */
+
+struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name)
+{
+	struct dma_chan *chan = dma_request_chan(dev, name);
+	int ret = 0;
+
+	if (!IS_ERR(chan))
+		ret = devm_add_action_or_reset(dev, dmaenginem_release_channel, chan);
+
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(devm_dma_request_chan);
+
 /**
  * dmaengine_get - register interest in dma_channels
  */
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 346251bf1026..ffb54b52ef0c 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1528,6 +1528,7 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
 
 struct dma_chan *dma_request_chan(struct device *dev, const char *name);
 struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask);
+struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name);
 
 void dma_release_channel(struct dma_chan *chan);
 int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps);
@@ -1564,6 +1565,12 @@ static inline struct dma_chan *dma_request_chan_by_mask(
 {
 	return ERR_PTR(-ENODEV);
 }
+
+static inline struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline void dma_release_channel(struct dma_chan *chan)
 {
 }
-- 
2.48.1

Re: [PATCH v2 1/4] dma: Add devm_dma_request_chan()

[Alexander Dahl]

Hello,

Am Fri, Jan 24, 2025 at 09:52:20AM +0100 schrieb Bence Csókás:
> Expand the arsenal of devm functions for DMA
> devices, this time for requesting channels.
> 
> Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
> ---
>  drivers/dma/dmaengine.c   | 30 ++++++++++++++++++++++++++++++
>  include/linux/dmaengine.h |  7 +++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index c1357d7f3dc6..02c29d26ac85 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -926,6 +926,36 @@ void dma_release_channel(struct dma_chan *chan)
>  }
>  EXPORT_SYMBOL_GPL(dma_release_channel);
>  
> +static void dmaenginem_release_channel(void *chan)
> +{
> +	dma_release_channel(chan);
> +}
> +
> +/**
> + * devm_dma_request_chan - try to allocate an exclusive slave channel
> + * @dev:	pointer to client device structure
> + * @name:	slave channel name
> + *
> + * Returns pointer to appropriate DMA channel on success or an error pointer.
> + *
> + * The operation is managed and will be undone on driver detach.
> + */
> +
> +struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name)
> +{
> +	struct dma_chan *chan = dma_request_chan(dev, name);
> +	int ret = 0;
> +
> +	if (!IS_ERR(chan))
> +		ret = devm_add_action_or_reset(dev, dmaenginem_release_channel, chan);

Why not using dma_release_channel() directly here?  What's the point
of introducing dmaenginem_release_channel() further above?

Greets
Alex

> +
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return chan;
> +}
> +EXPORT_SYMBOL_GPL(devm_dma_request_chan);
> +
>  /**
>   * dmaengine_get - register interest in dma_channels
>   */
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 346251bf1026..ffb54b52ef0c 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -1528,6 +1528,7 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
>  
>  struct dma_chan *dma_request_chan(struct device *dev, const char *name);
>  struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask);
> +struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name);
>  
>  void dma_release_channel(struct dma_chan *chan);
>  int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps);
> @@ -1564,6 +1565,12 @@ static inline struct dma_chan *dma_request_chan_by_mask(
>  {
>  	return ERR_PTR(-ENODEV);
>  }
> +
> +static inline struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +
>  static inline void dma_release_channel(struct dma_chan *chan)
>  {
>  }
> -- 
> 2.48.1
> 
> 
> 

Re: [PATCH v2 1/4] dma: Add devm_dma_request_chan()

[Csókás Bence]

Hi,

On 2025. 02. 03. 13:27, Alexander Dahl wrote:
>> +	if (!IS_ERR(chan))
>> +		ret = devm_add_action_or_reset(dev, dmaenginem_release_channel, chan);
> 
> Why not using dma_release_channel() directly here?  What's the point
> of introducing dmaenginem_release_channel() further above?

I followed the existing practice, used by 
`dmaenginem_async_device_unregister()`. I suspect it was done like this 
because the devm callback function's signature takes a `void *` and not 
`struct dma_chan *`.

Bence

[PATCH v2 2/4] pm: runtime: Add new devm functions

[Bence Csókás]

Add `devm_pm_runtime_set_active()` and
`devm_pm_runtime_get_noresume()` for
simplifying common use cases in drivers.

Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
---
 drivers/base/power/runtime.c | 36 ++++++++++++++++++++++++++++++++++++
 include/linux/pm_runtime.h   |  4 ++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 2ee45841486b..f0a6c64bec19 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1545,6 +1545,24 @@ void pm_runtime_enable(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(pm_runtime_enable);
 
+static void pm_runtime_set_suspended_action(void *data)
+{
+	pm_runtime_set_suspended(data);
+}
+
+/**
+ * devm_pm_runtime_set_active - devres-enabled version of pm_runtime_set_active.
+ *
+ * @dev: Device to handle.
+ */
+int devm_pm_runtime_set_active(struct device *dev)
+{
+	pm_runtime_set_active(dev);
+
+	return devm_add_action_or_reset(dev, pm_runtime_set_suspended_action, dev);
+}
+EXPORT_SYMBOL_GPL(devm_pm_runtime_set_active);
+
 static void pm_runtime_disable_action(void *data)
 {
 	pm_runtime_dont_use_autosuspend(data);
@@ -1567,6 +1585,24 @@ int devm_pm_runtime_enable(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(devm_pm_runtime_enable);
 
+static void pm_runtime_put_noidle_action(void *data)
+{
+	pm_runtime_put_noidle(data);
+}
+
+/**
+ * devm_pm_runtime_get_noresume - devres-enabled version of pm_runtime_get_noresume.
+ *
+ * @dev: Device to handle.
+ */
+int devm_pm_runtime_get_noresume(struct device *dev)
+{
+	pm_runtime_get_noresume(dev);
+
+	return devm_add_action_or_reset(dev, pm_runtime_put_noidle_action, dev);
+}
+EXPORT_SYMBOL_GPL(devm_pm_runtime_get_noresume);
+
 /**
  * pm_runtime_forbid - Block runtime PM of a device.
  * @dev: Device to handle.
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index d39dc863f612..d7eca86150b8 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -93,7 +93,9 @@ extern void pm_runtime_new_link(struct device *dev);
 extern void pm_runtime_drop_link(struct device_link *link);
 extern void pm_runtime_release_supplier(struct device_link *link);
 
+int devm_pm_runtime_set_active(struct device *dev);
 extern int devm_pm_runtime_enable(struct device *dev);
+int devm_pm_runtime_get_noresume(struct device *dev);
 
 /**
  * pm_suspend_ignore_children - Set runtime PM behavior regarding children.
@@ -276,7 +278,9 @@ static inline void __pm_runtime_disable(struct device *dev, bool c) {}
 static inline void pm_runtime_allow(struct device *dev) {}
 static inline void pm_runtime_forbid(struct device *dev) {}
 
+static inline int devm_pm_runtime_set_active(struct device *dev) { return 0; }
 static inline int devm_pm_runtime_enable(struct device *dev) { return 0; }
+static inline int devm_pm_runtime_get_noresume(struct device *dev) { return 0; }
 
 static inline void pm_suspend_ignore_children(struct device *dev, bool enable) {}
 static inline void pm_runtime_get_noresume(struct device *dev) {}
-- 
2.48.1

[PATCH v2 3/4] spi: atmel-quadspi: Use `devm_dma_request_chan()`

[Bence Csókás]

Leave releasing of DMA channels up to the devm
facilities. This way we can eliminate the rest
of the "goto ladder".

Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
---
 drivers/spi/atmel-quadspi.c | 44 ++++++++++---------------------------
 1 file changed, 11 insertions(+), 33 deletions(-)

diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
index abdc49d9d940..b1fb4426c78d 100644
--- a/drivers/spi/atmel-quadspi.c
+++ b/drivers/spi/atmel-quadspi.c
@@ -1288,18 +1288,20 @@ static int atmel_qspi_dma_init(struct spi_controller *ctrl)
 	struct atmel_qspi *aq = spi_controller_get_devdata(ctrl);
 	int ret;
 
-	aq->rx_chan = dma_request_chan(&aq->pdev->dev, "rx");
+	aq->rx_chan = devm_dma_request_chan(&aq->pdev->dev, "rx");
 	if (IS_ERR(aq->rx_chan)) {
 		aq->rx_chan = NULL;
 		return dev_err_probe(&aq->pdev->dev, PTR_ERR(aq->rx_chan),
 				     "RX DMA channel is not available\n");
 	}
 
-	aq->tx_chan = dma_request_chan(&aq->pdev->dev, "tx");
+	aq->tx_chan = devm_dma_request_chan(&aq->pdev->dev, "tx");
 	if (IS_ERR(aq->tx_chan)) {
 		ret = dev_err_probe(&aq->pdev->dev, PTR_ERR(aq->tx_chan),
 				    "TX DMA channel is not available\n");
-		goto release_rx_chan;
+		aq->rx_chan = NULL;
+		aq->tx_chan = NULL;
+		return ret;
 	}
 
 	ctrl->dma_rx = aq->rx_chan;
@@ -1310,20 +1312,6 @@ static int atmel_qspi_dma_init(struct spi_controller *ctrl)
 		 dma_chan_name(aq->tx_chan), dma_chan_name(aq->rx_chan));
 
 	return 0;
-
-release_rx_chan:
-	dma_release_channel(aq->rx_chan);
-	aq->rx_chan = NULL;
-	aq->tx_chan = NULL;
-	return ret;
-}
-
-static void atmel_qspi_dma_release(struct atmel_qspi *aq)
-{
-	if (aq->rx_chan)
-		dma_release_channel(aq->rx_chan);
-	if (aq->tx_chan)
-		dma_release_channel(aq->tx_chan);
 }
 
 static const struct atmel_qspi_ops atmel_qspi_ops = {
@@ -1428,14 +1416,13 @@ static int atmel_qspi_probe(struct platform_device *pdev)
 
 	/* Request the IRQ */
 	irq = platform_get_irq(pdev, 0);
-	if (irq < 0) {
-		err = irq;
-		goto dma_release;
-	}
+	if (irq < 0)
+		return irq;
+
 	err = devm_request_irq(&pdev->dev, irq, atmel_qspi_interrupt,
 			       0, dev_name(&pdev->dev), aq);
 	if (err)
-		goto dma_release;
+		return err;
 
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
 	pm_runtime_use_autosuspend(&pdev->dev);
@@ -1445,7 +1432,7 @@ static int atmel_qspi_probe(struct platform_device *pdev)
 
 	err = atmel_qspi_init(aq);
 	if (err)
-		goto dma_release;
+		return err;
 
 	err = spi_register_controller(ctrl);
 	if (err) {
@@ -1453,18 +1440,12 @@ static int atmel_qspi_probe(struct platform_device *pdev)
 		pm_runtime_disable(&pdev->dev);
 		pm_runtime_set_suspended(&pdev->dev);
 		pm_runtime_dont_use_autosuspend(&pdev->dev);
-		goto dma_release;
+		return err;
 	}
 	pm_runtime_mark_last_busy(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);
 
 	return 0;
-
-dma_release:
-	if (aq->caps->has_dma)
-		atmel_qspi_dma_release(aq);
-
-	return err;
 }
 
 static int atmel_qspi_sama7g5_suspend(struct atmel_qspi *aq)
@@ -1514,9 +1495,6 @@ static void atmel_qspi_remove(struct platform_device *pdev)
 
 	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret >= 0) {
-		if (aq->caps->has_dma)
-			atmel_qspi_dma_release(aq);
-
 		if (aq->caps->has_gclk) {
 			ret = atmel_qspi_sama7g5_suspend(aq);
 			if (ret)
-- 
2.48.1

[PATCH v2 4/4] spi: atmel-quadspi: Fix unbalanced pm_runtime by using devm_ API

[Bence Csókás]

Fix unbalanced PM in error path of `atmel_qspi_probe()`
by using `devm_pm_runtime_*()` functions.

Reported-by: Alexander Dahl <ada@thorsis.com>
Closes: https://lore.kernel.org/linux-spi/20250110-paycheck-irregular-bcddab1276c7@thorsis.com/
Fixes: 5af42209a4d2 ("spi: atmel-quadspi: Add support for sama7g5 QSPI")
Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
---
 drivers/spi/atmel-quadspi.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
index b1fb4426c78d..f2164685d3d5 100644
--- a/drivers/spi/atmel-quadspi.c
+++ b/drivers/spi/atmel-quadspi.c
@@ -1426,22 +1426,18 @@ static int atmel_qspi_probe(struct platform_device *pdev)
 
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
 	pm_runtime_use_autosuspend(&pdev->dev);
-	pm_runtime_set_active(&pdev->dev);
-	pm_runtime_enable(&pdev->dev);
-	pm_runtime_get_noresume(&pdev->dev);
+	devm_pm_runtime_set_active(&pdev->dev);
+	devm_pm_runtime_enable(&pdev->dev);
+	devm_pm_runtime_get_noresume(&pdev->dev);
 
 	err = atmel_qspi_init(aq);
 	if (err)
 		return err;
 
 	err = spi_register_controller(ctrl);
-	if (err) {
-		pm_runtime_put_noidle(&pdev->dev);
-		pm_runtime_disable(&pdev->dev);
-		pm_runtime_set_suspended(&pdev->dev);
-		pm_runtime_dont_use_autosuspend(&pdev->dev);
+	if (err)
 		return err;
-	}
+
 	pm_runtime_mark_last_busy(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);
 
@@ -1511,10 +1507,6 @@ static void atmel_qspi_remove(struct platform_device *pdev)
 		 */
 		dev_warn(&pdev->dev, "Failed to resume device on remove\n");
 	}
-
-	pm_runtime_disable(&pdev->dev);
-	pm_runtime_dont_use_autosuspend(&pdev->dev);
-	pm_runtime_put_noidle(&pdev->dev);
 }
 
 static int __maybe_unused atmel_qspi_suspend(struct device *dev)
-- 
2.48.1