Re: [PATCH] mt9v032: Use the common clock framework

[Sylwester Nawrocki <sylvester.nawrocki@gmail.com>]

Hi Laurent,

On 07/26/2013 03:15 PM, Laurent Pinchart wrote:
> On Friday 26 July 2013 15:11:08 Sylwester Nawrocki wrote:
>> On 07/05/2013 12:55 PM, Laurent Pinchart wrote:
>>> Configure the device external clock using the common clock framework
>>> instead of a board code callback function.
>>>
>>> Signed-off-by: Laurent Pinchart<laurent.pinchart@ideasonboard.com>
>>> ---
>>>
>>>    drivers/media/i2c/mt9v032.c | 16 ++++++++++------
>>>    include/media/mt9v032.h     |  4 ----
>>>    2 files changed, 10 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/media/i2c/mt9v032.c b/drivers/media/i2c/mt9v032.c
>>> index 60c6f67..7b30640 100644
>>> --- a/drivers/media/i2c/mt9v032.c
>>> +++ b/drivers/media/i2c/mt9v032.c
>>> @@ -12,6 +12,7 @@
>>>     * published by the Free Software Foundation.
>>>     */
>>>
>>> +#include<linux/clk.h>
>>>    #include<linux/delay.h>
>>>    #include<linux/i2c.h>
>>>    #include<linux/log2.h>
>>> @@ -135,6 +136,8 @@ struct mt9v032 {
>>>    	struct mutex power_lock;
>>>    	int power_count;
>>>
>>> +	struct clk *clk;
>>> +
>>>    	struct mt9v032_platform_data *pdata;
>>>    	
>>>    	u32 sysclk;
>>> @@ -219,10 +222,8 @@ static int mt9v032_power_on(struct mt9v032 *mt9v032)
>>>    	struct i2c_client *client = v4l2_get_subdevdata(&mt9v032->subdev);
>>>    	int ret;
>>>
>>> -	if (mt9v032->pdata->set_clock) {
>>> -		mt9v032->pdata->set_clock(&mt9v032->subdev, mt9v032->sysclk);
>>> -		udelay(1);
>>> -	}
>>> +	clk_prepare_enable(mt9v032->clk);
>>> +	udelay(1);
>>>
>>>    	/* Reset the chip and stop data read out */
>>>    	ret = mt9v032_write(client, MT9V032_RESET, 1);
>>> @@ -238,8 +239,7 @@ static int mt9v032_power_on(struct mt9v032 *mt9v032)
>>>
>>>    static void mt9v032_power_off(struct mt9v032 *mt9v032)
>>>    {
>>> -	if (mt9v032->pdata->set_clock)
>>> -		mt9v032->pdata->set_clock(&mt9v032->subdev, 0);
>>> +	clk_disable_unprepare(mt9v032->clk);
>>>    }
>>>
>>>    static int __mt9v032_set_power(struct mt9v032 *mt9v032, bool on)
>>> @@ -748,6 +748,10 @@ static int mt9v032_probe(struct i2c_client *client,
>>>    	if (!mt9v032)
>>>    		return -ENOMEM;
>>>
>>> +	mt9v032->clk = devm_clk_get(&client->dev, NULL);
>>> +	if (IS_ERR(mt9v032->clk))
>>> +		return PTR_ERR(mt9v032->clk);
>>> +
>>>    	mutex_init(&mt9v032->power_lock);
>>>    	mt9v032->pdata = pdata;
>>>
>>> diff --git a/include/media/mt9v032.h b/include/media/mt9v032.h
>>> index 78fd39e..12175a6 100644
>>> --- a/include/media/mt9v032.h
>>> +++ b/include/media/mt9v032.h
>>> @@ -1,13 +1,9 @@
>>>    #ifndef _MEDIA_MT9V032_H
>>>    #define _MEDIA_MT9V032_H
>>>
>>> -struct v4l2_subdev;
>>> -
>>>    struct mt9v032_platform_data {
>>>    	unsigned int clk_pol:1;
>>> -	void (*set_clock)(struct v4l2_subdev *subdev, unsigned int rate);
>>> -
>>>    	const s64 *link_freqs;
>>>    	s64 link_def_freq;
>>>    };
>>
>> Is there clk_put() somewhere in this patch ? I would expect it somewhere
>> around driver remove() callback, but can't see it. :-/
>
> There's *devm_*clk_get() instead :-)

Ah, I knew I must have been forgetting or overlooking something! ;)

Do you rely on the fact that __clk_get()/__clk_put() doesn't get reference
on the clock supplier module (to avoid locking modules in memory) ? I was
planning on adding module_get()/module_put() inside __clk_get()/__clk_out()
for the common clock API implementation.

Regards,
Sylwester