[PATCH v2 1/3] media: atmel-isi: remove the useless code which disable isi

[g.liakhovetski@gmx.de (Guennadi Liakhovetski)]

Hi Josh,

Thanks for the patch. I'm afraid I don't quite understand why it is 
needed, could you maybe explain a bit more? Is it because

(1) during ISI configuration the pixel clock from the sensor is (usually) 
anyway disabled, so, we don't have to additionally disable the ISI, 
without the pixel clock the ISI is anyway already disabled.

or

(2) disabling the ISI at those locations below breaks something, because 
when the ISI is disabled, the functionality, that's later used isn't 
available.

I assume it's (1), but if that's the case, then this patch is just 
cosmetic, right? The ISI is anyway disabled, so, that operation simply has 
no effect, but also doesn't hurt. OTOH, if some sensor keeps its master 
clock running all the time, then switching the ISI off as in the current 
version helps save some power, unless it breaks anything?

Thanks
Guennadi

On Thu, 9 Apr 2015, Josh Wu wrote:

> To program ISI control register, the pixel clock should be enabled.
> So without pixel clock (from sensor) enabled, disable ISI controller is
> not make sense. So this patch remove those code.
> 
> Signed-off-by: Josh Wu <josh.wu@atmel.com>
> ---
> 
> Changes in v2:
> - this file is new added.
> 
>  drivers/media/platform/soc_camera/atmel-isi.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/drivers/media/platform/soc_camera/atmel-isi.c b/drivers/media/platform/soc_camera/atmel-isi.c
> index c125b1d..31254b4 100644
> --- a/drivers/media/platform/soc_camera/atmel-isi.c
> +++ b/drivers/media/platform/soc_camera/atmel-isi.c
> @@ -131,8 +131,6 @@ static int configure_geometry(struct atmel_isi *isi, u32 width,
>  		return -EINVAL;
>  	}
>  
> -	isi_writel(isi, ISI_CTRL, ISI_CTRL_DIS);
> -
>  	cfg2 = isi_readl(isi, ISI_CFG2);
>  	/* Set YCC swap mode */
>  	cfg2 &= ~ISI_CFG2_YCC_SWAP_MODE_MASK;
> @@ -843,7 +841,6 @@ static int isi_camera_set_bus_param(struct soc_camera_device *icd)
>  
>  	cfg1 |= ISI_CFG1_THMASK_BEATS_16;
>  
> -	isi_writel(isi, ISI_CTRL, ISI_CTRL_DIS);
>  	isi_writel(isi, ISI_CFG1, cfg1);
>  
>  	return 0;
> @@ -1022,8 +1019,6 @@ static int atmel_isi_probe(struct platform_device *pdev)
>  	if (isi->pdata.data_width_flags & ISI_DATAWIDTH_10)
>  		isi->width_flags |= 1 << 9;
>  
> -	isi_writel(isi, ISI_CTRL, ISI_CTRL_DIS);
> -
>  	irq = platform_get_irq(pdev, 0);
>  	if (IS_ERR_VALUE(irq)) {
>  		ret = irq;
> -- 
> 1.9.1
>