[PATCH 1/2] i2c: stu300: use clk_prepare/unprepare

[PATCH 1/2] i2c: stu300: use clk_prepare/unprepare

[Linus Walleij]

From: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Make sure we prepare/unprepare the clock for the ST U300
I2C driver as is required by the clk API especially if you
use common clock.

Signed-off-by: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/i2c/busses/i2c-stu300.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-stu300.c b/drivers/i2c/busses/i2c-stu300.c
index 4d44af1..79b7851 100644
--- a/drivers/i2c/busses/i2c-stu300.c
+++ b/drivers/i2c/busses/i2c-stu300.c
@@ -924,7 +924,7 @@ stu300_probe(struct platform_device *pdev)
 
 	dev->speed = scl_frequency;
 
-	clk_enable(dev->clk);
+	clk_prepare_enable(dev->clk);
 	ret = stu300_init_hw(dev);
 	clk_disable(dev->clk);
 
@@ -960,6 +960,7 @@ stu300_probe(struct platform_device *pdev)
 
  err_add_adapter:
  err_init_hw:
+	clk_unprepare(dev->clk);
 	free_irq(dev->irq, dev);
  err_no_irq:
 	iounmap(dev->virtbase);
@@ -1016,6 +1017,7 @@ stu300_remove(struct platform_device *pdev)
 	free_irq(dev->irq, dev);
 	iounmap(dev->virtbase);
 	release_mem_region(dev->phybase, dev->physize);
+	clk_unprepare(dev->clk);
 	clk_put(dev->clk);
 	platform_set_drvdata(pdev, NULL);
 	kfree(dev);
-- 
1.7.9.2

Re: [PATCH 1/2] i2c: stu300: use clk_prepare/unprepare

[Shubhrajyoti Datta]

Hi Linus,

On Tue, Jun 12, 2012 at 11:03 PM, Linus Walleij
<linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org> wrote:
> From: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>
> Make sure we prepare/unprepare the clock for the ST U300
> I2C driver as is required by the clk API especially if you
> use common clock.
Not a comment rather a doubt.

The transfer is still using enable and disable?
Can you help me understand the difference.

>
> Signed-off-by: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-stu300.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-stu300.c b/drivers/i2c/busses/i2c-stu300.c
> index 4d44af1..79b7851 100644
> --- a/drivers/i2c/busses/i2c-stu300.c
> +++ b/drivers/i2c/busses/i2c-stu300.c
> @@ -924,7 +924,7 @@ stu300_probe(struct platform_device *pdev)
>
>        dev->speed = scl_frequency;
>
> -       clk_enable(dev->clk);
> +       clk_prepare_enable(dev->clk);
>        ret = stu300_init_hw(dev);
>        clk_disable(dev->clk);
>
> @@ -960,6 +960,7 @@ stu300_probe(struct platform_device *pdev)
>
>  err_add_adapter:
>  err_init_hw:
> +       clk_unprepare(dev->clk);

So this also fixes an earlier lack of disable also?

>        free_irq(dev->irq, dev);
>  err_no_irq:
>        iounmap(dev->virtbase);
> @@ -1016,6 +1017,7 @@ stu300_remove(struct platform_device *pdev)
>        free_irq(dev->irq, dev);
>        iounmap(dev->virtbase);
>        release_mem_region(dev->phybase, dev->physize);
> +       clk_unprepare(dev->clk);
>        clk_put(dev->clk);
>        platform_set_drvdata(pdev, NULL);
>        kfree(dev);
> --
> 1.7.9.2
>
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Re: [PATCH 1/2] i2c: stu300: use clk_prepare/unprepare

[Linus Walleij]

On Wed, Jun 13, 2012 at 8:22 AM, Shubhrajyoti Datta
<omaplinuxkernel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> <linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org> wrote:
>>
>> Make sure we prepare/unprepare the clock for the ST U300
>> I2C driver as is required by the clk API especially if you
>> use common clock.
>
> Not a comment rather a doubt.
>
> The transfer is still using enable and disable?
> Can you help me understand the difference.

Do you mean you want me to explain the difference
between enable/disable and prepare/unprepare?

>>  drivers/i2c/busses/i2c-stu300.c |    4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-stu300.c b/drivers/i2c/busses/i2c-stu300.c
>> index 4d44af1..79b7851 100644
>> --- a/drivers/i2c/busses/i2c-stu300.c
>> +++ b/drivers/i2c/busses/i2c-stu300.c
>> @@ -924,7 +924,7 @@ stu300_probe(struct platform_device *pdev)
>>
>>        dev->speed = scl_frequency;
>>
>> -       clk_enable(dev->clk);
>> +       clk_prepare_enable(dev->clk);
>>        ret = stu300_init_hw(dev);
>>        clk_disable(dev->clk);
>>
>> @@ -960,6 +960,7 @@ stu300_probe(struct platform_device *pdev)
>>
>>  err_add_adapter:
>>  err_init_hw:
>> +       clk_unprepare(dev->clk);
>
> So this also fixes an earlier lack of disable also?

No, there was no lack of disable earlier. If you look just a few lines
up in the patch there is a disable immediately after the
stu300_init_hw() call.

Yours,
Linus Walleij

Re: [PATCH 1/2] i2c: stu300: use clk_prepare/unprepare

[Wolfram Sang]

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On Tue, Jun 12, 2012 at 07:33:30PM +0200, Linus Walleij wrote:
> From: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> 
> Make sure we prepare/unprepare the clock for the ST U300
> I2C driver as is required by the clk API especially if you
> use common clock.
> 
> Signed-off-by: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Applied to next.

BTW sparse throws this for me, maybe you are interested:

drivers/i2c/busses/i2c-stu300.c:464:55: warning: cast removes address space of expression

Thanks,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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