Re: [PATCH 3/3] drm/i915: Revert backlight cargo-culting

[Takashi Iwai <tiwai@suse.de>]

At Fri, 22 Mar 2013 10:53:41 +0100,
Daniel Vetter wrote:
> 
> This reverts the following commits:
> 
> cf0a6584aa6d382f802 drm/i915: write backlight harder
> 770c12312ad617172b1 drm/i915: Fix blank panel at reopening lid
> 
> We've come full-circle in this mess and now broke the originally fixed
> machines again with the new trick. So remove it all and start over.
> 
> References: http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg18788.html
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Takashi Iwai <tiwai@suse.de>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Well, although I fully agree that it's better to clear all voodoo once
and fix from scratch, my concern is that it'll cause mess for stable
kernel.  This path won't fix anything by itself, so it's not suitable
for stable alone.  If any, it should be together with the real fix
patch.

I guess you'll submit the proper fix patch(es) to stable later on?


thanks,

Takashi

> ---
>  drivers/gpu/drm/i915/intel_panel.c |   10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index a3730e0..f31064a 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -336,7 +336,7 @@ void intel_panel_enable_backlight(struct drm_device *dev,
>  		 * we don't track the backlight dpms state, hence check whether
>  		 * we have to do anything first. */
>  		if (tmp & BLM_PWM_ENABLE)
> -			goto set_level;
> +			return;
>  
>  		if (dev_priv->num_pipe == 3)
>  			tmp &= ~BLM_PIPE_SELECT_IVB;
> @@ -357,14 +357,6 @@ void intel_panel_enable_backlight(struct drm_device *dev,
>  			I915_WRITE(BLC_PWM_PCH_CTL1, tmp);
>  		}
>  	}
> -
> -set_level:
> -	/* Check the current backlight level and try to set again if it's zero.
> -	 * On some machines, BLC_PWM_CPU_CTL is cleared to zero automatically
> -	 * when BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1 are written.
> -	 */
> -	if (!intel_panel_get_backlight(dev))
> -		intel_panel_actually_set_backlight(dev, dev_priv->backlight_level);
>  }
>  
>  static void intel_panel_init_backlight(struct drm_device *dev)
> -- 
> 1.7.10.4
>