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* [PATCH v3] i2c: designware: add reset interface
@ 2016-12-23 13:40 ` Zhangfei Gao
  0 siblings, 0 replies; 8+ messages in thread
From: Zhangfei Gao @ 2016-12-23 13:40 UTC (permalink / raw)
  To: Wolfram Sang, andriy.shevchenko, mika.westerberg, jarkko.nikula, p.zabel
  Cc: linux-arm-kernel, linux-i2c, Zhangfei Gao

Some platforms like hi3660 need do reset first to allow accessing registers

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Ramiro Oliveira <ramiro.oliveira@synopsys.com>
---
 drivers/i2c/busses/i2c-designware-core.h    |  1 +
 drivers/i2c/busses/i2c-designware-platdrv.c | 28 ++++++++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 0d44d2a..94b14fa 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -80,6 +80,7 @@ struct dw_i2c_dev {
 	void __iomem		*base;
 	struct completion	cmd_complete;
 	struct clk		*clk;
+	struct reset_control	*rst;
 	u32			(*get_clk_rate_khz) (struct dw_i2c_dev *dev);
 	struct dw_pci_controller *controller;
 	int			cmd_err;
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 0b42a12..1fbe66f 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -38,6 +38,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
 #include <linux/io.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/platform_data/i2c-designware.h>
@@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	dev->irq = irq;
 	platform_set_drvdata(pdev, dev);
 
+	dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(dev->rst)) {
+		if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+	} else {
+		reset_control_deassert(dev->rst);
+	}
+
 	/* fast mode by default because of legacy reasons */
 	dev->clk_freq = 400000;
 
@@ -207,12 +216,13 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	    && dev->clk_freq != 1000000 && dev->clk_freq != 3400000) {
 		dev_err(&pdev->dev,
 			"Only 100kHz, 400kHz, 1MHz and 3.4MHz supported");
-		return -EINVAL;
+		r = -EINVAL;
+		goto exit_reset;
 	}
 
 	r = i2c_dw_eval_lock_support(dev);
 	if (r)
-		return r;
+		goto exit_reset;
 
 	dev->functionality =
 		I2C_FUNC_I2C |
@@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	}
 
 	r = i2c_dw_probe(dev);
-	if (r && !dev->pm_runtime_disabled)
-		pm_runtime_disable(&pdev->dev);
+	if (r)
+		goto exit_probe;
 
 	return r;
+
+exit_probe:
+	if (!dev->pm_runtime_disabled)
+		pm_runtime_disable(&pdev->dev);
+exit_reset:
+	if (!IS_ERR_OR_NULL(dev->rst))
+		reset_control_assert(dev->rst);
+	return r;
 }
 
 static int dw_i2c_plat_remove(struct platform_device *pdev)
@@ -290,6 +308,8 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
 	pm_runtime_put_sync(&pdev->dev);
 	if (!dev->pm_runtime_disabled)
 		pm_runtime_disable(&pdev->dev);
+	if (!IS_ERR_OR_NULL(dev->rst))
+		reset_control_assert(dev->rst);
 
 	return 0;
 }
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [PATCH v3] i2c: designware: add reset interface
@ 2016-12-23 13:40 ` Zhangfei Gao
  0 siblings, 0 replies; 8+ messages in thread
From: Zhangfei Gao @ 2016-12-23 13:40 UTC (permalink / raw)
  To: linux-arm-kernel

Some platforms like hi3660 need do reset first to allow accessing registers

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Ramiro Oliveira <ramiro.oliveira@synopsys.com>
---
 drivers/i2c/busses/i2c-designware-core.h    |  1 +
 drivers/i2c/busses/i2c-designware-platdrv.c | 28 ++++++++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 0d44d2a..94b14fa 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -80,6 +80,7 @@ struct dw_i2c_dev {
 	void __iomem		*base;
 	struct completion	cmd_complete;
 	struct clk		*clk;
+	struct reset_control	*rst;
 	u32			(*get_clk_rate_khz) (struct dw_i2c_dev *dev);
 	struct dw_pci_controller *controller;
 	int			cmd_err;
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 0b42a12..1fbe66f 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -38,6 +38,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
 #include <linux/io.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/platform_data/i2c-designware.h>
@@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	dev->irq = irq;
 	platform_set_drvdata(pdev, dev);
 
+	dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(dev->rst)) {
+		if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+	} else {
+		reset_control_deassert(dev->rst);
+	}
+
 	/* fast mode by default because of legacy reasons */
 	dev->clk_freq = 400000;
 
@@ -207,12 +216,13 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	    && dev->clk_freq != 1000000 && dev->clk_freq != 3400000) {
 		dev_err(&pdev->dev,
 			"Only 100kHz, 400kHz, 1MHz and 3.4MHz supported");
-		return -EINVAL;
+		r = -EINVAL;
+		goto exit_reset;
 	}
 
 	r = i2c_dw_eval_lock_support(dev);
 	if (r)
-		return r;
+		goto exit_reset;
 
 	dev->functionality =
 		I2C_FUNC_I2C |
@@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	}
 
 	r = i2c_dw_probe(dev);
-	if (r && !dev->pm_runtime_disabled)
-		pm_runtime_disable(&pdev->dev);
+	if (r)
+		goto exit_probe;
 
 	return r;
+
+exit_probe:
+	if (!dev->pm_runtime_disabled)
+		pm_runtime_disable(&pdev->dev);
+exit_reset:
+	if (!IS_ERR_OR_NULL(dev->rst))
+		reset_control_assert(dev->rst);
+	return r;
 }
 
 static int dw_i2c_plat_remove(struct platform_device *pdev)
@@ -290,6 +308,8 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
 	pm_runtime_put_sync(&pdev->dev);
 	if (!dev->pm_runtime_disabled)
 		pm_runtime_disable(&pdev->dev);
+	if (!IS_ERR_OR_NULL(dev->rst))
+		reset_control_assert(dev->rst);
 
 	return 0;
 }
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 8+ messages in thread
* Re: [PATCH v3] i2c: designware: add reset interface
  2016-12-23 13:40 ` Zhangfei Gao
@ 2017-01-04 14:55   ` Arnd Bergmann
  -1 siblings, 0 replies; 8+ messages in thread
From: Arnd Bergmann @ 2017-01-04 14:55 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: Zhangfei Gao, Wolfram Sang, andriy.shevchenko, mika.westerberg,
	jarkko.nikula, p.zabel, linux-i2c

On Friday, December 23, 2016 9:40:51 PM CET Zhangfei Gao wrote:
> @@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>         dev->irq = irq;
>         platform_set_drvdata(pdev, dev);
>  
> +       dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
> +       if (IS_ERR(dev->rst)) {
> +               if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
> +                       return -EPROBE_DEFER;
> +       } else {
> +               reset_control_deassert(dev->rst);
> +       }
> +

Sorry for the late reply, I only now stumbled over this. I think it's
generally wrong to ignore any error aside from -EPROBE_DEFER. It's
better to single-out the error conditions you want to ignore (e.g.
no reset specified) and ignore those but return an error for
all other problems.

> @@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>         }
>  
>         r = i2c_dw_probe(dev);
> -       if (r && !dev->pm_runtime_disabled)
> -               pm_runtime_disable(&pdev->dev);
> +       if (r)
> +               goto exit_probe;
>  
>         return r;
> +
> +exit_probe:
> +       if (!dev->pm_runtime_disabled)
> +               pm_runtime_disable(&pdev->dev);
> +exit_reset:
> +       if (!IS_ERR_OR_NULL(dev->rst))
> +               reset_control_assert(dev->rst);
> +       return r;
> 

try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
a bad interface, or that the interface is used wrong.

In this case, I think we can't get here with a NULL dev->rst
pointer, so it's better to only check IS_ERR, or to explicitly
set the pointer to NULL in case there is no reset line.

	Arnd

^ permalink raw reply	[flat|nested] 8+ messages in thread
* [PATCH v3] i2c: designware: add reset interface
@ 2017-01-04 14:55   ` Arnd Bergmann
  0 siblings, 0 replies; 8+ messages in thread
From: Arnd Bergmann @ 2017-01-04 14:55 UTC (permalink / raw)
  To: linux-arm-kernel

On Friday, December 23, 2016 9:40:51 PM CET Zhangfei Gao wrote:
> @@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>         dev->irq = irq;
>         platform_set_drvdata(pdev, dev);
>  
> +       dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
> +       if (IS_ERR(dev->rst)) {
> +               if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
> +                       return -EPROBE_DEFER;
> +       } else {
> +               reset_control_deassert(dev->rst);
> +       }
> +

Sorry for the late reply, I only now stumbled over this. I think it's
generally wrong to ignore any error aside from -EPROBE_DEFER. It's
better to single-out the error conditions you want to ignore (e.g.
no reset specified) and ignore those but return an error for
all other problems.

> @@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>         }
>  
>         r = i2c_dw_probe(dev);
> -       if (r && !dev->pm_runtime_disabled)
> -               pm_runtime_disable(&pdev->dev);
> +       if (r)
> +               goto exit_probe;
>  
>         return r;
> +
> +exit_probe:
> +       if (!dev->pm_runtime_disabled)
> +               pm_runtime_disable(&pdev->dev);
> +exit_reset:
> +       if (!IS_ERR_OR_NULL(dev->rst))
> +               reset_control_assert(dev->rst);
> +       return r;
> 

try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
a bad interface, or that the interface is used wrong.

In this case, I think we can't get here with a NULL dev->rst
pointer, so it's better to only check IS_ERR, or to explicitly
set the pointer to NULL in case there is no reset line.

	Arnd

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH v3] i2c: designware: add reset interface
  2017-01-04 14:55   ` Arnd Bergmann
@ 2017-01-04 15:35     ` Andy Shevchenko
  -1 siblings, 0 replies; 8+ messages in thread
From: Andy Shevchenko @ 2017-01-04 15:35 UTC (permalink / raw)
  To: Arnd Bergmann, linux-arm-kernel
  Cc: Zhangfei Gao, Wolfram Sang, mika.westerberg, jarkko.nikula,
	p.zabel, linux-i2c

On Wed, 2017-01-04 at 15:55 +0100, Arnd Bergmann wrote:
> On Friday, December 23, 2016 9:40:51 PM CET Zhangfei Gao wrote:
> > @@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct
> > platform_device *pdev)
> >         dev->irq = irq;
> >         platform_set_drvdata(pdev, dev);
> >  
> > +       dev->rst = devm_reset_control_get_optional_exclusive(&pdev-
> > >dev, NULL);
> > +       if (IS_ERR(dev->rst)) {
> > +               if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
> > +                       return -EPROBE_DEFER;
> > +       } else {
> > +               reset_control_deassert(dev->rst);
> > +       }
> > +
> 
> Sorry for the late reply, I only now stumbled over this. I think it's
> generally wrong to ignore any error aside from -EPROBE_DEFER. It's
> better to single-out the error conditions you want to ignore (e.g.
> no reset specified) and ignore those but return an error for
> all other problems.

Which means that reset framework whenever work _optional is used should
return error iff (mind two f:s) there is a problem with existing
control.

> 
> > @@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct
> > platform_device *pdev)
> >         }
> >  
> >         r = i2c_dw_probe(dev);
> > -       if (r && !dev->pm_runtime_disabled)
> > -               pm_runtime_disable(&pdev->dev);
> > +       if (r)
> > +               goto exit_probe;
> >  
> >         return r;
> > +
> > +exit_probe:
> > +       if (!dev->pm_runtime_disabled)
> > +               pm_runtime_disable(&pdev->dev);
> > +exit_reset:
> > +       if (!IS_ERR_OR_NULL(dev->rst))
> > +               reset_control_assert(dev->rst);
> > +       return r;
> > 
> 
> try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
> a bad interface, or that the interface is used wrong.

Please, fix reset framework first than.

For my understanding:
It should return NULL for optional reset control.
It should not fail on NULL argument.


> In this case, I think we can't get here with a NULL dev->rst
> pointer, so it's better to only check IS_ERR, or to explicitly
> set the pointer to NULL in case there is no reset line.
> 
> 	Arnd

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

^ permalink raw reply	[flat|nested] 8+ messages in thread
* [PATCH v3] i2c: designware: add reset interface
@ 2017-01-04 15:35     ` Andy Shevchenko
  0 siblings, 0 replies; 8+ messages in thread
From: Andy Shevchenko @ 2017-01-04 15:35 UTC (permalink / raw)
  To: linux-arm-kernel

On Wed, 2017-01-04 at 15:55 +0100, Arnd Bergmann wrote:
> On Friday, December 23, 2016 9:40:51 PM CET Zhangfei Gao wrote:
> > @@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct
> > platform_device *pdev)
> > ????????dev->irq = irq;
> > ????????platform_set_drvdata(pdev, dev);
> > ?
> > +???????dev->rst = devm_reset_control_get_optional_exclusive(&pdev-
> > >dev, NULL);
> > +???????if (IS_ERR(dev->rst)) {
> > +???????????????if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
> > +???????????????????????return -EPROBE_DEFER;
> > +???????} else {
> > +???????????????reset_control_deassert(dev->rst);
> > +???????}
> > +
> 
> Sorry for the late reply, I only now stumbled over this. I think it's
> generally wrong to ignore any error aside from -EPROBE_DEFER. It's
> better to single-out the error conditions you want to ignore (e.g.
> no reset specified) and ignore those but return an error for
> all other problems.

Which means that reset framework whenever work _optional is used should
return error iff (mind two f:s) there is a problem with existing
control.

> 
> > @@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct
> > platform_device *pdev)
> > ????????}
> > ?
> > ????????r = i2c_dw_probe(dev);
> > -???????if (r && !dev->pm_runtime_disabled)
> > -???????????????pm_runtime_disable(&pdev->dev);
> > +???????if (r)
> > +???????????????goto exit_probe;
> > ?
> > ????????return r;
> > +
> > +exit_probe:
> > +???????if (!dev->pm_runtime_disabled)
> > +???????????????pm_runtime_disable(&pdev->dev);
> > +exit_reset:
> > +???????if (!IS_ERR_OR_NULL(dev->rst))
> > +???????????????reset_control_assert(dev->rst);
> > +???????return r;
> > 
> 
> try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
> a bad interface, or that the interface is used wrong.

Please, fix reset framework first than.

For my understanding:
It should return NULL for optional reset control.
It should not fail on NULL argument.


> In this case, I think we can't get here with a NULL dev->rst
> pointer, so it's better to only check IS_ERR, or to explicitly
> set the pointer to NULL in case there is no reset line.
> 
> 	Arnd

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH v3] i2c: designware: add reset interface
  2017-01-04 15:35     ` Andy Shevchenko
@ 2017-01-06 11:32       ` Arnd Bergmann
  -1 siblings, 0 replies; 8+ messages in thread
From: Arnd Bergmann @ 2017-01-06 11:32 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: Wolfram Sang, jarkko.nikula, linux-i2c, p.zabel, Zhangfei Gao,
	Andy Shevchenko, mika.westerberg

On Wednesday, January 4, 2017 5:35:19 PM CET Andy Shevchenko wrote:


> > > @@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct
> > > platform_device *pdev)
> > >         }
> > >  
> > >         r = i2c_dw_probe(dev);
> > > -       if (r && !dev->pm_runtime_disabled)
> > > -               pm_runtime_disable(&pdev->dev);
> > > +       if (r)
> > > +               goto exit_probe;
> > >  
> > >         return r;
> > > +
> > > +exit_probe:
> > > +       if (!dev->pm_runtime_disabled)
> > > +               pm_runtime_disable(&pdev->dev);
> > > +exit_reset:
> > > +       if (!IS_ERR_OR_NULL(dev->rst))
> > > +               reset_control_assert(dev->rst);
> > > +       return r;
> > > 
> > 
> > try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
> > a bad interface, or that the interface is used wrong.
> 
> Please, fix reset framework first than.
> 
> For my understanding:
> It should return NULL for optional reset control.
> It should not fail on NULL argument.

I think we discussed that a few times. Your suggestion makes sense
to me, but I don't know why we don't already do that, maybe there
is a good reason.

	Arnd

^ permalink raw reply	[flat|nested] 8+ messages in thread
* [PATCH v3] i2c: designware: add reset interface
@ 2017-01-06 11:32       ` Arnd Bergmann
  0 siblings, 0 replies; 8+ messages in thread
From: Arnd Bergmann @ 2017-01-06 11:32 UTC (permalink / raw)
  To: linux-arm-kernel

On Wednesday, January 4, 2017 5:35:19 PM CET Andy Shevchenko wrote:


> > > @@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct
> > > platform_device *pdev)
> > >         }
> > >  
> > >         r = i2c_dw_probe(dev);
> > > -       if (r && !dev->pm_runtime_disabled)
> > > -               pm_runtime_disable(&pdev->dev);
> > > +       if (r)
> > > +               goto exit_probe;
> > >  
> > >         return r;
> > > +
> > > +exit_probe:
> > > +       if (!dev->pm_runtime_disabled)
> > > +               pm_runtime_disable(&pdev->dev);
> > > +exit_reset:
> > > +       if (!IS_ERR_OR_NULL(dev->rst))
> > > +               reset_control_assert(dev->rst);
> > > +       return r;
> > > 
> > 
> > try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
> > a bad interface, or that the interface is used wrong.
> 
> Please, fix reset framework first than.
> 
> For my understanding:
> It should return NULL for optional reset control.
> It should not fail on NULL argument.

I think we discussed that a few times. Your suggestion makes sense
to me, but I don't know why we don't already do that, maybe there
is a good reason.

	Arnd

^ permalink raw reply	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2017-01-06 11:32 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-12-23 13:40 [PATCH v3] i2c: designware: add reset interface Zhangfei Gao
2016-12-23 13:40 ` Zhangfei Gao
2017-01-04 14:55 ` Arnd Bergmann
2017-01-04 14:55   ` Arnd Bergmann
2017-01-04 15:35   ` Andy Shevchenko
2017-01-04 15:35     ` Andy Shevchenko
2017-01-06 11:32     ` Arnd Bergmann
2017-01-06 11:32       ` Arnd Bergmann

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