RE: [PATCH] video: s3c-fb: Make runtime PM functional again

[Jingoo Han]

Hi, Mark

Mark wrote:
> -----Original Message-----
> Subject: [PATCH] video: s3c-fb: Make runtime PM functional again
> 
> The change in "video: s3c-fb: modify runtime pm functions" (commit
> 35784b) renders the runtime power management for the device completely
> ineffectual as while it leaves runtime power management notionally
> enabled a runtime power reference is held for the entire time the device
> is registered meaning it will never actually do anything.
> 
> A further issue is introduced as runtime power management is added
> during the system suspend path which is not something which drivers are
> supposed to do and would interact poorly if there were any operations
> done in the runtime power management callbacks.
> 
> While this does make things simpler (the main motivation for the
> original change) it will not only cause us to use more power in the
> framebuffer controller but will also prevent us entering lower power
> domain and SoC wide states as we can never power down the domain
> containing the device.  Since neither of these things is desirable
> revert the change.
The main difference is as follows:
If no fb windows are opened.
	- Your patch: LCD block power is off
	- My patch: LCD block power is on still.

However, after booting, probing, open is called from platform system, soon.
And, the default window is always opened. This means that at least one window
is opened after booting. So, I don't think that "video: s3c-fb: modify runtime
pm functions" (commit: 35784b) cause us to use more power in the framebuffer
controller.

My intention is that runtime pm is used only for LCD block power off when
suspend and resume are called.

> 
> Signed-off-by: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/video/s3c-fb.c |   51 +++++++++++++++++++++++++++++------------------
>  1 files changed, 31 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/video/s3c-fb.c b/drivers/video/s3c-fb.c
> index e531ebc..690b44e 100644
> --- a/drivers/video/s3c-fb.c
> +++ b/drivers/video/s3c-fb.c
> @@ -1036,8 +1036,30 @@ static int s3c_fb_ioctl(struct fb_info *info, unsigned int cmd,
>  	return ret;
>  }
> 
> +static int s3c_fb_open(struct fb_info *info, int user)
> +{
> +	struct s3c_fb_win *win = info->par;
> +	struct s3c_fb *sfb = win->parent;
> +
> +	pm_runtime_get_sync(sfb->dev);
> +
> +	return 0;
> +}
> +
> +static int s3c_fb_release(struct fb_info *info, int user)
> +{
> +	struct s3c_fb_win *win = info->par;
> +	struct s3c_fb *sfb = win->parent;
> +
> +	pm_runtime_put_sync(sfb->dev);
> +
> +	return 0;
> +}
> +
>  static struct fb_ops s3c_fb_ops = {
>  	.owner		= THIS_MODULE,
> +	.fb_open	= s3c_fb_open,
> +	.fb_release	= s3c_fb_release,
>  	.fb_check_var	= s3c_fb_check_var,
>  	.fb_set_par	= s3c_fb_set_par,
>  	.fb_blank	= s3c_fb_blank,
> @@ -1436,6 +1458,7 @@ static int __devinit s3c_fb_probe(struct platform_device *pdev)
>  	}
> 
>  	platform_set_drvdata(pdev, sfb);
> +	pm_runtime_put_sync(sfb->dev);
> 
>  	return 0;
> 
> @@ -1468,6 +1491,8 @@ static int __devexit s3c_fb_remove(struct platform_device *pdev)
>  	struct s3c_fb *sfb = platform_get_drvdata(pdev);
>  	int win;
> 
> +	pm_runtime_get_sync(sfb->dev);
> +
>  	for (win = 0; win < S3C_FB_MAX_WIN; win++)
>  		if (sfb->windows[win])
>  			s3c_fb_release_win(sfb, sfb->windows[win]);
> @@ -1488,7 +1513,7 @@ static int __devexit s3c_fb_remove(struct platform_device *pdev)
>  	return 0;
>  }
> 
> -#ifdef CONFIG_PM_SLEEP
> +#ifdef CONFIG_PM
>  static int s3c_fb_suspend(struct device *dev)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
> @@ -1509,8 +1534,6 @@ static int s3c_fb_suspend(struct device *dev)
>  		clk_disable(sfb->lcd_clk);
> 
>  	clk_disable(sfb->bus_clk);
> -	pm_runtime_put_sync(sfb->dev);
> -
>  	return 0;
>  }
> 
> @@ -1522,7 +1545,6 @@ static int s3c_fb_resume(struct device *dev)
>  	struct s3c_fb_win *win;
>  	int win_no;
> 
> -	pm_runtime_get_sync(sfb->dev);
>  	clk_enable(sfb->bus_clk);
> 
>  	if (!sfb->variant.has_clksel)
> @@ -1561,19 +1583,11 @@ static int s3c_fb_resume(struct device *dev)
> 
>  	return 0;
>  }
> +#else
> +#define s3c_fb_suspend NULL
> +#define s3c_fb_resume  NULL
>  #endif
> 
> -#ifdef CONFIG_PM_RUNTIME
> -static int s3c_fb_runtime_suspend(struct device *dev)
> -{
> -	return 0;
> -}
> -
> -static int s3c_fb_runtime_resume(struct device *dev)
> -{
> -	return 0;
> -}
> -#endif
> 
>  #define VALID_BPP124 (VALID_BPP(1) | VALID_BPP(2) | VALID_BPP(4))
>  #define VALID_BPP1248 (VALID_BPP124 | VALID_BPP(8))
> @@ -1896,10 +1910,7 @@ static struct platform_device_id s3c_fb_driver_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(platform, s3c_fb_driver_ids);
> 
> -static const struct dev_pm_ops s3c_fb_pm_ops = {
> -	SET_SYSTEM_SLEEP_PM_OPS(s3c_fb_suspend, s3c_fb_resume)
> -	SET_RUNTIME_PM_OPS(s3c_fb_runtime_suspend, s3c_fb_runtime_resume, NULL)
> -};
> +static UNIVERSAL_DEV_PM_OPS(s3cfb_pm_ops, s3c_fb_suspend, s3c_fb_resume, NULL);
> 
>  static struct platform_driver s3c_fb_driver = {
>  	.probe		= s3c_fb_probe,
> @@ -1908,7 +1919,7 @@ static struct platform_driver s3c_fb_driver = {
>  	.driver		= {
>  		.name	= "s3c-fb",
>  		.owner	= THIS_MODULE,
> -		.pm	= &s3c_fb_pm_ops,
> +		.pm	= &s3cfb_pm_ops,
>  	},
>  };
> 
> --
> 1.7.7.3
> 
> --
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