[02/20] mt9m111: init chip after read CHIP_VERSION

  Moved mt9m111_init after the chip version detection passage: I
don't like the idea of writing on a device we haven't identified
yet.

Signed-off-by: Philipp Wiesner <p.wiesner@phytec.de>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
---
 drivers/media/video/mt9m111.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)
  

On Fri, 30 Jul 2010, Michael Grzeschik wrote:

> Moved mt9m111_init after the chip version detection passage: I
> don't like the idea of writing on a device we haven't identified
> yet.

In principle it's correct, but what do you do, if a chip cannot be probed, 
before it is initialised / enabled? Actually, this shouldn't be the case, 
devices should be available for probing without any initialisation. So, we 
have to ask the original author, whether this really was necessary, 
Robert?

Thanks
Guennadi

> 
> Signed-off-by: Philipp Wiesner <p.wiesner@phytec.de>
> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
> ---
>  drivers/media/video/mt9m111.c |    6 ++----
>  1 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/video/mt9m111.c b/drivers/media/video/mt9m111.c
> index e934559..39dff7c 100644
> --- a/drivers/media/video/mt9m111.c
> +++ b/drivers/media/video/mt9m111.c
> @@ -969,10 +969,6 @@ static int mt9m111_video_probe(struct soc_camera_device *icd,
>  	mt9m111->swap_rgb_even_odd = 1;
>  	mt9m111->swap_rgb_red_blue = 1;
>  
> -	ret = mt9m111_init(client);
> -	if (ret)
> -		goto ei2c;
> -
>  	data = reg_read(CHIP_VERSION);
>  
>  	switch (data) {
> @@ -994,6 +990,8 @@ static int mt9m111_video_probe(struct soc_camera_device *icd,
>  		goto ei2c;
>  	}
>  
> +	ret = mt9m111_init(client);
> +
>  ei2c:
>  	return ret;
>  }
> -- 
> 1.7.1
> 
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
  

Guennadi Liakhovetski <g.liakhovetski@gmx.de> writes:

> On Fri, 30 Jul 2010, Michael Grzeschik wrote:
>
>> Moved mt9m111_init after the chip version detection passage: I
>> don't like the idea of writing on a device we haven't identified
>> yet.
>
> In principle it's correct, but what do you do, if a chip cannot be probed, 
> before it is initialised / enabled? Actually, this shouldn't be the case, 
> devices should be available for probing without any initialisation. So, we 
> have to ask the original author, whether this really was necessary, 
> Robert?

Michael is right I think.
According to the specification, even before the reset, the control registers can
be read, and they'll return their current values, which can be weird before
reset, excepting the CHIP_VERSION which is hard coded.

Therefore I think Michael is right by reading chip version before doing the
reset, and I ack this patch.

Cheers.