[RESEND PATCH 0/3] Allow on demand channel request / free

[RESEND PATCH 0/3] Allow on demand channel request / free

[Daniel Baluta]

From: Daniel Baluta <daniel.baluta@nxp.com>

Requesting an mailbox channel will call mailbox's startup
function.

startup function calls pm_runtime_get_sync which increments device usage
count and will keep the device active. Specifically, mailbox clock will
be always ON when a mailbox channel is requested.

For this, reason we introduce a way to request/free IMX DSP channels
on demand to save power when the channels are not used.

First two patches are doing code refactoring preparing the path
for 3rd patch which exports functions for on demand channel request/free

Daniel Baluta (3):
  firmware: imx: Introduce imx_dsp_setup_channels
  firmware: imx: Save channel name for further use
  firmware: imx-dsp: Export functions to request/free channels

 drivers/firmware/imx/imx-dsp.c   | 72 ++++++++++++++++++++++++--------
 include/linux/firmware/imx/dsp.h | 10 +++++
 2 files changed, 64 insertions(+), 18 deletions(-)

-- 
2.17.1


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[RESEND PATCH 1/3] firmware: imx: Introduce imx_dsp_setup_channels

[Daniel Baluta]

From: Daniel Baluta <daniel.baluta@nxp.com>

Create a separate function that sets up DSP mailbox channels
so that imx_dsp_probe function will be easier to read.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
---
 drivers/firmware/imx/imx-dsp.c | 41 +++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/drivers/firmware/imx/imx-dsp.c b/drivers/firmware/imx/imx-dsp.c
index 4265e9dbed84..a3a018c87b52 100644
--- a/drivers/firmware/imx/imx-dsp.c
+++ b/drivers/firmware/imx/imx-dsp.c
@@ -60,22 +60,15 @@ static void imx_dsp_handle_rx(struct mbox_client *c, void *msg)
 	}
 }
 
-static int imx_dsp_probe(struct platform_device *pdev)
+static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
 {
-	struct device *dev = &pdev->dev;
-	struct imx_dsp_ipc *dsp_ipc;
+	struct device *dev = dsp_ipc->dev;
 	struct imx_dsp_chan *dsp_chan;
 	struct mbox_client *cl;
 	char *chan_name;
 	int ret;
 	int i, j;
 
-	device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent);
-
-	dsp_ipc = devm_kzalloc(dev, sizeof(*dsp_ipc), GFP_KERNEL);
-	if (!dsp_ipc)
-		return -ENOMEM;
-
 	for (i = 0; i < DSP_MU_CHAN_NUM; i++) {
 		if (i < 2)
 			chan_name = kasprintf(GFP_KERNEL, "txdb%d", i);
@@ -108,12 +101,6 @@ static int imx_dsp_probe(struct platform_device *pdev)
 		kfree(chan_name);
 	}
 
-	dsp_ipc->dev = dev;
-
-	dev_set_drvdata(dev, dsp_ipc);
-
-	dev_info(dev, "NXP i.MX DSP IPC initialized\n");
-
 	return 0;
 out:
 	kfree(chan_name);
@@ -125,6 +112,30 @@ static int imx_dsp_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static int imx_dsp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct imx_dsp_ipc *dsp_ipc;
+	int ret;
+
+	device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent);
+
+	dsp_ipc = devm_kzalloc(dev, sizeof(*dsp_ipc), GFP_KERNEL);
+	if (!dsp_ipc)
+		return -ENOMEM;
+
+	dsp_ipc->dev = dev;
+	dev_set_drvdata(dev, dsp_ipc);
+
+	ret = imx_dsp_setup_channels(dsp_ipc);
+	if (ret < 0)
+		return ret;
+
+	dev_info(dev, "NXP i.MX DSP IPC initialized\n");
+
+	return 0;
+}
+
 static int imx_dsp_remove(struct platform_device *pdev)
 {
 	struct imx_dsp_chan *dsp_chan;
-- 
2.17.1


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[RESEND PATCH 2/3] firmware: imx: Save channel name for further use

[Daniel Baluta]

From: Daniel Baluta <daniel.baluta@nxp.com>

We want to request / free channels on demand later in order
to save power.

For this for each channel we save the name and use it to
reference the channel later.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
---
 drivers/firmware/imx/imx-dsp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/imx/imx-dsp.c b/drivers/firmware/imx/imx-dsp.c
index a3a018c87b52..b6e95d6d34c0 100644
--- a/drivers/firmware/imx/imx-dsp.c
+++ b/drivers/firmware/imx/imx-dsp.c
@@ -79,6 +79,7 @@ static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
 			return -ENOMEM;
 
 		dsp_chan = &dsp_ipc->chans[i];
+		dsp_chan->name = chan_name;
 		cl = &dsp_chan->cl;
 		cl->dev = dev;
 		cl->tx_block = false;
@@ -97,16 +98,14 @@ static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
 		}
 
 		dev_dbg(dev, "request mbox chan %s\n", chan_name);
-		/* chan_name is not used anymore by framework */
-		kfree(chan_name);
 	}
 
 	return 0;
 out:
-	kfree(chan_name);
 	for (j = 0; j < i; j++) {
 		dsp_chan = &dsp_ipc->chans[j];
 		mbox_free_channel(dsp_chan->ch);
+		kfree(dsp_chan->name);
 	}
 
 	return ret;
@@ -147,6 +146,7 @@ static int imx_dsp_remove(struct platform_device *pdev)
 	for (i = 0; i < DSP_MU_CHAN_NUM; i++) {
 		dsp_chan = &dsp_ipc->chans[i];
 		mbox_free_channel(dsp_chan->ch);
+		kfree(dsp_chan->name);
 	}
 
 	return 0;
-- 
2.17.1


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[RESEND PATCH 3/3] firmware: imx-dsp: Export functions to request/free channels

[Daniel Baluta]

From: Daniel Baluta <daniel.baluta@nxp.com>

In order to save power, we only need to request a channel
when the communication with the DSP active.

For this we export the following functions:
	- imx_dsp_request_channel, gets a channel with a given index
	- imx_dsp_free_channel, frees a channel with a given index

Notice that we still request channels at probe to support devices
that do not have PM callbacks implemented.

More explanations about why requesting a channel has an effect
on power savings:
 - requesting an mailbox channel will call mailbox's startup
   function.
 - startup function calls pm_runtime_get_sync which increments device
   usage count and will keep the device active. Specifically, mailbox
   clock will be always ON when a mailbox channel is requested.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
---
 drivers/firmware/imx/imx-dsp.c   | 25 +++++++++++++++++++++++++
 include/linux/firmware/imx/dsp.h | 10 ++++++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/firmware/imx/imx-dsp.c b/drivers/firmware/imx/imx-dsp.c
index b6e95d6d34c0..a6c06d7476c3 100644
--- a/drivers/firmware/imx/imx-dsp.c
+++ b/drivers/firmware/imx/imx-dsp.c
@@ -60,6 +60,31 @@ static void imx_dsp_handle_rx(struct mbox_client *c, void *msg)
 	}
 }
 
+struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *dsp_ipc, int idx)
+{
+	struct imx_dsp_chan *dsp_chan;
+
+	if (idx >= DSP_MU_CHAN_NUM)
+		return ERR_PTR(-EINVAL);
+
+	dsp_chan = &dsp_ipc->chans[idx];
+	dsp_chan->ch = mbox_request_channel_byname(&dsp_chan->cl, dsp_chan->name);
+	return dsp_chan->ch;
+}
+EXPORT_SYMBOL(imx_dsp_request_channel);
+
+void imx_dsp_free_channel(struct imx_dsp_ipc *dsp_ipc, int idx)
+{
+	struct imx_dsp_chan *dsp_chan;
+
+	if (idx >= DSP_MU_CHAN_NUM)
+		return;
+
+	dsp_chan = &dsp_ipc->chans[idx];
+	mbox_free_channel(dsp_chan->ch);
+}
+EXPORT_SYMBOL(imx_dsp_free_channel);
+
 static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
 {
 	struct device *dev = dsp_ipc->dev;
diff --git a/include/linux/firmware/imx/dsp.h b/include/linux/firmware/imx/dsp.h
index 7562099c9e46..4f7895a3b73c 100644
--- a/include/linux/firmware/imx/dsp.h
+++ b/include/linux/firmware/imx/dsp.h
@@ -55,6 +55,9 @@ static inline void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
 
 int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
 
+struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *ipc, int idx);
+void imx_dsp_free_channel(struct imx_dsp_ipc *ipc, int idx);
+
 #else
 
 static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
@@ -63,5 +66,12 @@ static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
 	return -ENOTSUPP;
 }
 
+struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *ipc, int idx)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+void imx_dsp_free_channel(struct imx_dsp_ipc *ipc, int idx) { }
+
 #endif
 #endif /* _IMX_DSP_IPC_H */
-- 
2.17.1


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