[Intel-gfx] [PATCH] drm/i915: Decrease pll->refcount when freeze gpu

[Jesse Barnes]

On Thu, 11 Jul 2013 16:02:27 +0800
Xiong Zhang <xiong.y.zhang at intel.com> wrote:

> display.crtc_mode_set will increase pll->refcount, but no one will
> decrease pll->refcount when freeze gpu. So when gpu resume from freeze,
> pll->refcount is still larger than zero. This is abnormal
> 
> Without this patch, connecting vga screen on Haswell platform, there
> are following results:
> 1. when resume S3, call trace exist in intel_ddi_put_crtc_pll()
> 2. when resume s4, vga monitor is black. because intel_ddi_pll_mode_set()
>    return false and haswell_crtc_mode_set() exit without setting mode
> 
> With this patch, I don't find S3 and S4 regression on SandyBridge
> and IvyBridge platform connecting VGA, HDMI and DP screen.
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 0485f43..0065735 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -575,8 +575,10 @@ static int i915_drm_freeze(struct drm_device *dev)
>  		 * Disable CRTCs directly since we want to preserve sw state
>  		 * for _thaw.
>  		 */
> -		list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
> +		list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
>  			dev_priv->display.crtc_disable(crtc);
> +			dev_priv->display.off(crtc);
> +		}
>  
>  		intel_modeset_suspend_hw(dev);
>  	}

The comment above this call indicates we'll trash the sw state if we
call ->off directly.  Does suspend/resume still work both with and
without X with this patch applied?  If we trash the sw state, the VT
switchless resume shouldn't work...

-- 
Jesse Barnes, Intel Open Source Technology Center