Patchwork i2c: sh_mobile: Don't start transfers when suspending

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Submitter Bastian Hecht
Date Feb. 14, 2013, 5:17 p.m.
Message ID <1360862257-10807-1-git-send-email-hechtb+renesas@gmail.com>
Download mbox | patch
Permalink /patch/220469/
State Changes Requested
Headers show

Comments

Bastian Hecht - Feb. 14, 2013, 5:17 p.m.
Currently we provoke i2c timeouts by allowing transfers when
suspending. This patch adds awareness to suspending and fixes these
issues.
The patch follows the style used in i2c-tegra.c - thanks.

Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
---
 drivers/i2c/busses/i2c-sh_mobile.c |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
Simon Horman - Feb. 16, 2013, 2:26 a.m.
On Thu, Feb 14, 2013 at 11:17:37AM -0600, Bastian Hecht wrote:
> Currently we provoke i2c timeouts by allowing transfers when
> suspending. This patch adds awareness to suspending and fixes these
> issues.
> The patch follows the style used in i2c-tegra.c - thanks.

Hi,

at this stage I do not expect this code to go through the renesas tree.
However, in order to provide a basis for work on renesas SoCs I have added
this patch to the topic/i2c topic branch in the reneas tree on
kernel.org and merged it into topic/all+next.

In other words, I am not picking this patch up to merge it or add it to
linux-next, rather I am storing it for reference.

> 
> Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
> ---
>  drivers/i2c/busses/i2c-sh_mobile.c |   28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
> index b6e7a83..da28164 100644
> --- a/drivers/i2c/busses/i2c-sh_mobile.c
> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> @@ -132,6 +132,7 @@ struct sh_mobile_i2c_data {
>  	struct i2c_msg *msg;
>  	int pos;
>  	int sr;
> +	bool is_suspended;
>  };
>  
>  #define IIC_FLAG_HAS_ICIC67	(1 << 0)
> @@ -511,6 +512,9 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
>  	u_int8_t val;
>  	int i, k, retry_count;
>  
> +	if (pd->is_suspended)
> +		return -EBUSY;
> +
>  	activate_ch(pd);
>  
>  	/* Process all messages */
> @@ -753,9 +757,33 @@ static int sh_mobile_i2c_runtime_nop(struct device *dev)
>  	return 0;
>  }
>  
> +static int sh_mobile_i2c_suspend(struct device *dev)
> +{
> +	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
> +
> +	i2c_lock_adapter(&pd->adap);
> +	pd->is_suspended = true;
> +	i2c_unlock_adapter(&pd->adap);
> +
> +	return 0;
> +}
> +
> +static int sh_mobile_i2c_resume(struct device *dev)
> +{
> +	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
> +
> +	i2c_lock_adapter(&pd->adap);
> +	pd->is_suspended = false;
> +	i2c_unlock_adapter(&pd->adap);
> +
> +	return 0;
> +}
> +
>  static const struct dev_pm_ops sh_mobile_i2c_dev_pm_ops = {
>  	.runtime_suspend = sh_mobile_i2c_runtime_nop,
>  	.runtime_resume = sh_mobile_i2c_runtime_nop,
> +	.suspend = sh_mobile_i2c_suspend,
> +	.resume = sh_mobile_i2c_resume,
>  };
>  
>  static const struct of_device_id sh_mobile_i2c_dt_ids[] = {
> -- 
> 1.7.9.5
> 
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Magnus Damm - Feb. 16, 2013, 3:54 a.m.
On Fri, Feb 15, 2013 at 2:17 AM, Bastian Hecht <hechtb@gmail.com> wrote:
> Currently we provoke i2c timeouts by allowing transfers when
> suspending. This patch adds awareness to suspending and fixes these
> issues.
> The patch follows the style used in i2c-tegra.c - thanks.
>
> Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
> ---
>  drivers/i2c/busses/i2c-sh_mobile.c |   28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
> index b6e7a83..da28164 100644
> --- a/drivers/i2c/busses/i2c-sh_mobile.c
> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> @@ -132,6 +132,7 @@ struct sh_mobile_i2c_data {
>         struct i2c_msg *msg;
>         int pos;
>         int sr;
> +       bool is_suspended;
>  };
>
>  #define IIC_FLAG_HAS_ICIC67    (1 << 0)
> @@ -511,6 +512,9 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
>         u_int8_t val;
>         int i, k, retry_count;
>
> +       if (pd->is_suspended)
> +               return -EBUSY;
> +
>         activate_ch(pd);
>
>         /* Process all messages */
> @@ -753,9 +757,33 @@ static int sh_mobile_i2c_runtime_nop(struct device *dev)
>         return 0;
>  }
>
> +static int sh_mobile_i2c_suspend(struct device *dev)
> +{
> +       struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
> +
> +       i2c_lock_adapter(&pd->adap);
> +       pd->is_suspended = true;
> +       i2c_unlock_adapter(&pd->adap);
> +
> +       return 0;
> +}
> +
> +static int sh_mobile_i2c_resume(struct device *dev)
> +{
> +       struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
> +
> +       i2c_lock_adapter(&pd->adap);
> +       pd->is_suspended = false;
> +       i2c_unlock_adapter(&pd->adap);
> +
> +       return 0;
> +}
> +
>  static const struct dev_pm_ops sh_mobile_i2c_dev_pm_ops = {
>         .runtime_suspend = sh_mobile_i2c_runtime_nop,
>         .runtime_resume = sh_mobile_i2c_runtime_nop,
> +       .suspend = sh_mobile_i2c_suspend,
> +       .resume = sh_mobile_i2c_resume,
>  };
>
>  static const struct of_device_id sh_mobile_i2c_dt_ids[] = {
> --

Hi Bastian,

Thanks for your work on this. Can you tell us a bit more about where
and when this fix is needed? I am guessing here, but perhaps it only
triggers on SMP hardware with CONFIG_SMP enabled?

Also, do you know the reason why this isn't handled in the i2c layer
by default? I ask because your comment mentions that i2c-tegra.c does
the same thing and I can't see anything in this patch that is actually
related to our I2C hardware.

Thanks,

/ magnus
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Bastian Hecht - Feb. 18, 2013, 4:03 p.m.
2013/2/15 Magnus Damm <magnus.damm@gmail.com>:
> On Fri, Feb 15, 2013 at 2:17 AM, Bastian Hecht <hechtb@gmail.com> wrote:
>> Currently we provoke i2c timeouts by allowing transfers when
>> suspending. This patch adds awareness to suspending and fixes these
>> issues.
>> The patch follows the style used in i2c-tegra.c - thanks.
>>
>> Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
>> ---
>>  drivers/i2c/busses/i2c-sh_mobile.c |   28 ++++++++++++++++++++++++++++
>>  1 file changed, 28 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
>> index b6e7a83..da28164 100644
>> --- a/drivers/i2c/busses/i2c-sh_mobile.c
>> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
>> @@ -132,6 +132,7 @@ struct sh_mobile_i2c_data {
>>         struct i2c_msg *msg;
>>         int pos;
>>         int sr;
>> +       bool is_suspended;
>>  };
>>
>>  #define IIC_FLAG_HAS_ICIC67    (1 << 0)
>> @@ -511,6 +512,9 @@ static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
>>         u_int8_t val;
>>         int i, k, retry_count;
>>
>> +       if (pd->is_suspended)
>> +               return -EBUSY;
>> +
>>         activate_ch(pd);
>>
>>         /* Process all messages */
>> @@ -753,9 +757,33 @@ static int sh_mobile_i2c_runtime_nop(struct device *dev)
>>         return 0;
>>  }
>>
>> +static int sh_mobile_i2c_suspend(struct device *dev)
>> +{
>> +       struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
>> +
>> +       i2c_lock_adapter(&pd->adap);
>> +       pd->is_suspended = true;
>> +       i2c_unlock_adapter(&pd->adap);
>> +
>> +       return 0;
>> +}
>> +
>> +static int sh_mobile_i2c_resume(struct device *dev)
>> +{
>> +       struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
>> +
>> +       i2c_lock_adapter(&pd->adap);
>> +       pd->is_suspended = false;
>> +       i2c_unlock_adapter(&pd->adap);
>> +
>> +       return 0;
>> +}
>> +
>>  static const struct dev_pm_ops sh_mobile_i2c_dev_pm_ops = {
>>         .runtime_suspend = sh_mobile_i2c_runtime_nop,
>>         .runtime_resume = sh_mobile_i2c_runtime_nop,
>> +       .suspend = sh_mobile_i2c_suspend,
>> +       .resume = sh_mobile_i2c_resume,
>>  };
>>
>>  static const struct of_device_id sh_mobile_i2c_dt_ids[] = {
>> --
>
> Hi Bastian,
>
> Thanks for your work on this. Can you tell us a bit more about where
> and when this fix is needed? I am guessing here, but perhaps it only
> triggers on SMP hardware with CONFIG_SMP enabled?

It appears on the UP r8a7740 on my Armadillo. I didn't succeed in
quickly triggering it on the sh73a0.

> Also, do you know the reason why this isn't handled in the i2c layer
> by default? I ask because your comment mentions that i2c-tegra.c does
> the same thing and I can't see anything in this patch that is actually
> related to our I2C hardware.

Yes, many drivers have a similar scheme and to me it more looked like
all drivers need to take care about this case unrelated to different
hardware. So the question arises if this can't be handled in the core
- or if I get something wrong here. I can have a deeper look later at
this when the issues in "[PATCH] input: st1232: Add IRQF_NO_SUSPEND
flag" become more clear and we can work on it without side effects of
other bugs. So I suppose we should stall this patch until then.

Thanks,

 Bastian


> Thanks,
>
> / magnus
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Wolfram Sang - Feb. 21, 2013, 9:14 a.m.
Hi Bastian,

> > Also, do you know the reason why this isn't handled in the i2c layer
> > by default? I ask because your comment mentions that i2c-tegra.c does
> > the same thing and I can't see anything in this patch that is actually
> > related to our I2C hardware.
> 
> Yes, many drivers have a similar scheme and to me it more looked like
> all drivers need to take care about this case unrelated to different
> hardware. So the question arises if this can't be handled in the core
> - or if I get something wrong here.

I don't see any reason why this couldn't be handled in the core. If you
want to have a take on this issue (after the other bug is fixed), this
will be highly appreciated.

Thanks,

   Wolfram

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Bastian Hecht - Feb. 21, 2013, 2:54 p.m.
Hi Wolfram,

oh yes I can gladly do so. To make a realistic estimation it might
take a few weeks until I find time for it though. If we can wait so
long, count on me.

Best,

 Bastian

2013/2/21 Wolfram Sang <wsa@the-dreams.de>:
> Hi Bastian,
>
>> > Also, do you know the reason why this isn't handled in the i2c layer
>> > by default? I ask because your comment mentions that i2c-tegra.c does
>> > the same thing and I can't see anything in this patch that is actually
>> > related to our I2C hardware.
>>
>> Yes, many drivers have a similar scheme and to me it more looked like
>> all drivers need to take care about this case unrelated to different
>> hardware. So the question arises if this can't be handled in the core
>> - or if I get something wrong here.
>
> I don't see any reason why this couldn't be handled in the core. If you
> want to have a take on this issue (after the other bug is fixed), this
> will be highly appreciated.
>
> Thanks,
>
>    Wolfram
>
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Wolfram Sang - Feb. 21, 2013, 2:59 p.m.
> oh yes I can gladly do so. To make a realistic estimation it might
> take a few weeks until I find time for it though. If we can wait so
> long, count on me.

Totally fine with me.

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Patch

diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index b6e7a83..da28164 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -132,6 +132,7 @@  struct sh_mobile_i2c_data {
 	struct i2c_msg *msg;
 	int pos;
 	int sr;
+	bool is_suspended;
 };
 
 #define IIC_FLAG_HAS_ICIC67	(1 << 0)
@@ -511,6 +512,9 @@  static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
 	u_int8_t val;
 	int i, k, retry_count;
 
+	if (pd->is_suspended)
+		return -EBUSY;
+
 	activate_ch(pd);
 
 	/* Process all messages */
@@ -753,9 +757,33 @@  static int sh_mobile_i2c_runtime_nop(struct device *dev)
 	return 0;
 }
 
+static int sh_mobile_i2c_suspend(struct device *dev)
+{
+	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
+
+	i2c_lock_adapter(&pd->adap);
+	pd->is_suspended = true;
+	i2c_unlock_adapter(&pd->adap);
+
+	return 0;
+}
+
+static int sh_mobile_i2c_resume(struct device *dev)
+{
+	struct sh_mobile_i2c_data *pd = dev_get_drvdata(dev);
+
+	i2c_lock_adapter(&pd->adap);
+	pd->is_suspended = false;
+	i2c_unlock_adapter(&pd->adap);
+
+	return 0;
+}
+
 static const struct dev_pm_ops sh_mobile_i2c_dev_pm_ops = {
 	.runtime_suspend = sh_mobile_i2c_runtime_nop,
 	.runtime_resume = sh_mobile_i2c_runtime_nop,
+	.suspend = sh_mobile_i2c_suspend,
+	.resume = sh_mobile_i2c_resume,
 };
 
 static const struct of_device_id sh_mobile_i2c_dt_ids[] = {