Discussion:
[PATCH v3 0/3] i2c/at91: add support PM functions
(too old to reply)
Wenyou Yang
2014-10-24 06:53:23 UTC
Permalink
Hi Wolfram,

The patches is to add the PM functions support for the at91 i2c controller.

It is based on the i2c/for-next branch of
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git.

Best Regards,
Wenyou Yang

------
Change log:
v2.0

According to the advice from Kevin Hilman,
1./ Wrap the runtime suspend/resume functions in CONFIG_PM instead of CONFIG_PM_RUNTIME.
2./ Call the runtime suspend/resume functions directly in the system suspend/resume.

v3.0
Covert the system suspend/resume to suspend_noirq/resume_noirq.

Wenyou Yang (3):
i2c/at91: add support for runtime PM
i2c/at91: add support for system PM
i2c/at91: adopt pinctrl support

drivers/i2c/busses/i2c-at91.c | 71 +++++++++++++++++++++++++++++++++++++----
1 file changed, 65 insertions(+), 6 deletions(-)
--
1.7.9.5

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Wenyou Yang
2014-10-24 06:54:13 UTC
Permalink
Drivers should put the device into low power states proactively whenever the
device is not in use. Thus implement support for runtime PM and use the
autosuspend feature to make sure that we can still perform well in case we see
lots of i2c traffic within short period of time.

Signed-off-by: Wenyou Yang <***@atmel.com>
---
drivers/i2c/busses/i2c-at91.c | 38 ++++++++++++++++++++++++++++++++------
1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 917d545..a25fb5e 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -31,10 +31,12 @@
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/platform_data/dma-atmel.h>
+#include <linux/pm_runtime.h>

#define DEFAULT_TWI_CLK_HZ 100000 /* max 400 Kbits/s */
#define AT91_I2C_TIMEOUT msecs_to_jiffies(100) /* transfer timeout */
#define AT91_I2C_DMA_THRESHOLD 8 /* enable DMA if transfer size is bigger than this threshold */
+#define AUTOSUSPEND_TIMEOUT 2000

/* AT91 TWI register definitions */
#define AT91_TWI_CR 0x0000 /* Control Register */
@@ -481,6 +483,10 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)

dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);

+ ret = pm_runtime_get_sync(dev->dev);
+ if (ret < 0)
+ goto out;
+
/*
* The hardware can handle at most two messages concatenated by a
* repeated start via it's internal address feature.
@@ -488,18 +494,21 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
if (num > 2) {
dev_err(dev->dev,
"cannot handle more than two concatenated messages.\n");
- return 0;
+ ret = 0;
+ goto out;
} else if (num == 2) {
int internal_address = 0;
int i;

if (msg->flags & I2C_M_RD) {
dev_err(dev->dev, "first transfer must be write.\n");
- return -EINVAL;
+ ret = -EINVAL;
+ goto out;
}
if (msg->len > 3) {
dev_err(dev->dev, "first message size must be <= 3.\n");
- return -EINVAL;
+ ret = -EINVAL;
+ goto out;
}

/* 1st msg is put into the internal address, start with 2nd */
@@ -523,7 +532,12 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)

ret = at91_do_twi_transfer(dev);

- return (ret < 0) ? ret : num;
+ ret = (ret < 0) ? ret : num;
+out:
+ pm_runtime_mark_last_busy(dev->dev);
+ pm_runtime_put_autosuspend(dev->dev);
+
+ return ret;
}

static u32 at91_twi_func(struct i2c_adapter *adapter)
@@ -795,11 +809,20 @@ static int at91_twi_probe(struct platform_device *pdev)
dev->adapter.timeout = AT91_I2C_TIMEOUT;
dev->adapter.dev.of_node = pdev->dev.of_node;

+ pm_runtime_set_autosuspend_delay(dev->dev, AUTOSUSPEND_TIMEOUT);
+ pm_runtime_use_autosuspend(dev->dev);
+ pm_runtime_set_active(dev->dev);
+ pm_runtime_enable(dev->dev);
+
rc = i2c_add_numbered_adapter(&dev->adapter);
if (rc) {
dev_err(dev->dev, "Adapter %s registration failed\n",
dev->adapter.name);
clk_disable_unprepare(dev->clk);
+
+ pm_runtime_disable(dev->dev);
+ pm_runtime_set_suspended(dev->dev);
+
return rc;
}

@@ -814,6 +837,9 @@ static int at91_twi_remove(struct platform_device *pdev)
i2c_del_adapter(&dev->adapter);
clk_disable_unprepare(dev->clk);

+ pm_runtime_disable(dev->dev);
+ pm_runtime_set_suspended(dev->dev);
+
return 0;
}

@@ -823,7 +849,7 @@ static int at91_twi_runtime_suspend(struct device *dev)
{
struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);

- clk_disable(twi_dev->clk);
+ clk_disable_unprepare(twi_dev->clk);

return 0;
}
@@ -832,7 +858,7 @@ static int at91_twi_runtime_resume(struct device *dev)
{
struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);

- return clk_enable(twi_dev->clk);
+ return clk_prepare_enable(twi_dev->clk);
}

static const struct dev_pm_ops at91_twi_pm = {
--
1.7.9.5

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Wenyou Yang
2014-10-24 06:55:02 UTC
Permalink
Signed-off-by: Wenyou Yang <***@atmel.com>
---
drivers/i2c/busses/i2c-at91.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index a25fb5e..6a84a2a 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -861,7 +861,33 @@ static int at91_twi_runtime_resume(struct device *dev)
return clk_prepare_enable(twi_dev->clk);
}

+static int at91_twi_suspend_noirq(struct device *dev)
+{
+ if (!pm_runtime_status_suspended(dev))
+ at91_twi_runtime_suspend(dev);
+
+ return 0;
+}
+
+static int at91_twi_resume_noirq(struct device *dev)
+{
+ int ret;
+
+ if (!pm_runtime_status_suspended(dev)) {
+ ret = at91_twi_runtime_resume(dev);
+ if (ret)
+ return ret;
+ }
+
+ pm_runtime_mark_last_busy(dev);
+ pm_request_autosuspend(dev);
+
+ return 0;
+}
+
static const struct dev_pm_ops at91_twi_pm = {
+ .suspend_noirq = at91_twi_suspend_noirq,
+ .resume_noirq = at91_twi_resume_noirq,
.runtime_suspend = at91_twi_runtime_suspend,
.runtime_resume = at91_twi_runtime_resume,
};
--
1.7.9.5

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Sergei Shtylyov
2014-10-24 13:03:02 UTC
Permalink
Hello.
Post by Wenyou Yang
---
drivers/i2c/busses/i2c-at91.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index a25fb5e..6a84a2a 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -861,7 +861,33 @@ static int at91_twi_runtime_resume(struct device *dev)
[...]
Post by Wenyou Yang
+static int at91_twi_resume_noirq(struct device *dev)
+{
+ int ret;
+
+ if (!pm_runtime_status_suspended(dev)) {
+ ret = at91_twi_runtime_resume(dev);
Resume if *not* suspended?
Post by Wenyou Yang
+ if (ret)
+ return ret;
+ }
+
+ pm_runtime_mark_last_busy(dev);
+ pm_request_autosuspend(dev);
+
+ return 0;
+}
+
[...]

WBR, Sergei

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Yang, Wenyou
2014-10-27 00:37:31 UTC
Permalink
Hi,
-----Original Message-----
Sent: Friday, October 24, 2014 9:03 PM
Subject: Re: [PATCH v3 2/3] i2c/at91: add support for system PM
Hello.
Post by Wenyou Yang
---
drivers/i2c/busses/i2c-at91.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/i2c/busses/i2c-at91.c
b/drivers/i2c/busses/i2c-at91.c index a25fb5e..6a84a2a 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -861,7 +861,33 @@ static int at91_twi_runtime_resume(struct device *dev)
[...]
Post by Wenyou Yang
+static int at91_twi_resume_noirq(struct device *dev) {
+ int ret;
+
+ if (!pm_runtime_status_suspended(dev)) {
+ ret = at91_twi_runtime_resume(dev);
Resume if *not* suspended?
Yes, if it is not runtime_suspended, it must be the system suspended, then resume it. I think so.
Post by Wenyou Yang
+ if (ret)
+ return ret;
+ }
+
+ pm_runtime_mark_last_busy(dev);
+ pm_request_autosuspend(dev);
+
+ return 0;
+}
+
[...]
WBR, Sergei
Best Regards,
Wenyou Yang
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Wenyou Yang
2014-10-24 06:55:46 UTC
Permalink
Amend the i2c at91 pin controller to optionally take a pin control
handle and set the state of the pins to:

- "default" on boot, resume and before performing an transfer
- "sleep" on suspend()

This should make it possible to optimize energy usage for the pins
both for the suspend/resume cycle

Signed-off-by: Wenyou Yang <***@atmel.com>
---
drivers/i2c/busses/i2c-at91.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 6a84a2a..290caf1 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -32,6 +32,7 @@
#include <linux/slab.h>
#include <linux/platform_data/dma-atmel.h>
#include <linux/pm_runtime.h>
+#include <linux/pinctrl/consumer.h>

#define DEFAULT_TWI_CLK_HZ 100000 /* max 400 Kbits/s */
#define AT91_I2C_TIMEOUT msecs_to_jiffies(100) /* transfer timeout */
@@ -747,6 +748,8 @@ static int at91_twi_probe(struct platform_device *pdev)
u32 phy_addr;
u32 bus_clk_rate;

+ pinctrl_pm_select_default_state(&pdev->dev);
+
dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
if (!dev)
return -ENOMEM;
@@ -851,6 +854,8 @@ static int at91_twi_runtime_suspend(struct device *dev)

clk_disable_unprepare(twi_dev->clk);

+ pinctrl_pm_select_sleep_state(dev);
+
return 0;
}

@@ -858,6 +863,8 @@ static int at91_twi_runtime_resume(struct device *dev)
{
struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);

+ pinctrl_pm_select_default_state(dev);
+
return clk_prepare_enable(twi_dev->clk);
}
--
1.7.9.5

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Yang, Wenyou
2014-11-10 01:52:53 UTC
Permalink
Hi Wolfram,
-----Original Message-----
Sent: Sunday, November 09, 2014 2:03 AM
To: Yang, Wenyou
Subject: Re: [PATCH v3 3/3] i2c/at91: adopt pinctrl support
Post by Wenyou Yang
Amend the i2c at91 pin controller to optionally take a pin control
- "default" on boot, resume and before performing an transfer
- "sleep" on suspend()
This should make it possible to optimize energy usage for the pins
both for the suspend/resume cycle
---
drivers/i2c/busses/i2c-at91.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/i2c/busses/i2c-at91.c
b/drivers/i2c/busses/i2c-at91.c index 6a84a2a..290caf1 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -32,6 +32,7 @@
#include <linux/slab.h>
#include <linux/platform_data/dma-atmel.h> #include
<linux/pm_runtime.h>
+#include <linux/pinctrl/consumer.h>
#define DEFAULT_TWI_CLK_HZ 100000 /* max 400 Kbits/s
*/
Post by Wenyou Yang
#define AT91_I2C_TIMEOUT msecs_to_jiffies(100) /* transfer timeout */
@@ -747,6 +748,8 @@ static int at91_twi_probe(struct platform_device *pdev)
u32 phy_addr;
u32 bus_clk_rate;
+ pinctrl_pm_select_default_state(&pdev->dev);
+
Do we really need this in probe? Isn't that default? I'm not sure, though...
No, we don't need it.
It is called by the function pinctrl_bind_pins(struct device *dev) in drivers/base/pinctrl.c

I will remove it, and send it again.
Post by Wenyou Yang
dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
if (!dev)
return -ENOMEM;
@@ -851,6 +854,8 @@ static int at91_twi_runtime_suspend(struct device *dev)
clk_disable_unprepare(twi_dev->clk);
+ pinctrl_pm_select_sleep_state(dev);
+
return 0;
}
@@ -858,6 +863,8 @@ static int at91_twi_runtime_resume(struct device
*dev) {
struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
+ pinctrl_pm_select_default_state(dev);
+
return clk_prepare_enable(twi_dev->clk); }
--
1.7.9.5
Best Regards,
Wenyou Yang
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Ludovic Desroches
2014-10-29 08:24:39 UTC
Permalink
For the whole serie
Post by Wenyou Yang
Hi Wolfram,
The patches is to add the PM functions support for the at91 i2c controller.
It is based on the i2c/for-next branch of
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git.
Best Regards,
Wenyou Yang
------
v2.0
According to the advice from Kevin Hilman,
1./ Wrap the runtime suspend/resume functions in CONFIG_PM instead of CONFIG_PM_RUNTIME.
2./ Call the runtime suspend/resume functions directly in the system suspend/resume.
v3.0
Covert the system suspend/resume to suspend_noirq/resume_noirq.
i2c/at91: add support for runtime PM
i2c/at91: add support for system PM
i2c/at91: adopt pinctrl support
drivers/i2c/busses/i2c-at91.c | 71 +++++++++++++++++++++++++++++++++++++----
1 file changed, 65 insertions(+), 6 deletions(-)
--
1.7.9.5
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Yang, Wenyou
2014-11-05 10:05:58 UTC
Permalink
Hi Wolfram,

Could you give me some advice? Thank you in advance.
-----Original Message-----
Sent: Wednesday, October 29, 2014 4:24 PM
To: Yang, Wenyou
Subject: Re: [PATCH v3 0/3] i2c/at91: add support PM functions
For the whole serie
Post by Wenyou Yang
Hi Wolfram,
The patches is to add the PM functions support for the at91 i2c controller.
It is based on the i2c/for-next branch of
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git.
Best Regards,
Wenyou Yang
------
v2.0
According to the advice from Kevin Hilman, 1./ Wrap the runtime
suspend/resume functions in CONFIG_PM instead of CONFIG_PM_RUNTIME.
2./ Call the runtime suspend/resume functions directly in the system
suspend/resume.
Post by Wenyou Yang
v3.0
Covert the system suspend/resume to suspend_noirq/resume_noirq.
i2c/at91: add support for runtime PM
i2c/at91: add support for system PM
i2c/at91: adopt pinctrl support
drivers/i2c/busses/i2c-at91.c | 71
+++++++++++++++++++++++++++++++++++++----
Post by Wenyou Yang
1 file changed, 65 insertions(+), 6 deletions(-)
--
1.7.9.5
Best Regards,
Wenyou Yang
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