[Intel-gfx] [PATCH] drm/i915: vlv: fix stuck primary plane due to SR watermarks

[Daniel Vetter]

On Fri, May 30, 2014 at 09:07:19AM +0300, Imre Deak wrote:
> Blanking/unblanking the console in a loop on an Asus T100 sometimes
> leaves the console blank. After some digging I found that applying
> 
> commit 61bc95c1fbbb6a08b55bbe161fdf1ea5493fc595
> Author: Egbert Eich <eich at suse.com>
> Date:   Mon Mar 4 09:24:38 2013 -0500
> 
>     DRM/i915: On G45 enable cursor plane briefly after enabling the display plane.
> 
> fixed VLV too. At least in my case the problem seems to happen already
> during the previous crtc disabling, and it goes away if we disable SR
> watermarks before disabling the primary plane.
> 
> I also noticed that the problem only happens if the C7S CPU idle state
> is entered, disabling that also gets rid of the problem. As an
> alternative I also tried to increase the plane SR watermark close to its
> maximum but that didn't solve the issue.
> 
> Signed-off-by: Imre Deak <imre.deak at intel.com>

Can we please escalate this a bit with the hw guys? Duct-tape for g4x is
kinda ok, but imo for byt we should try harder ...
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_drv.h      | 1 +
>  drivers/gpu/drm/i915/intel_display.c | 9 +++++++++
>  drivers/gpu/drm/i915/intel_pm.c      | 7 +++++++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index bea9ab40..afee677 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2591,6 +2591,7 @@ extern void gen6_set_rps(struct drm_device *dev, u8 val);
>  extern void valleyview_set_rps(struct drm_device *dev, u8 val);
>  extern int valleyview_rps_max_freq(struct drm_i915_private *dev_priv);
>  extern int valleyview_rps_min_freq(struct drm_i915_private *dev_priv);
> +extern void valleyview_disable_sr_watermarks(struct drm_i915_private *dev_priv);
>  extern void intel_detect_pch(struct drm_device *dev);
>  extern int intel_trans_dp_port_sel(struct drm_crtc *crtc);
>  extern int intel_enable_rc6(const struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 54095d4..11611e1 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4767,6 +4767,15 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
>  	if (IS_GEN2(dev))
>  		intel_set_cpu_fifo_underrun_reporting(dev, pipe, false);
>  
> +	/*
> +	 * Having the SR WMs enabled when disabling the primary plane may
> +	 * leave the primary plane in a stuck state, where it wouldn't
> +	 * start fetching pixels after a subsequent crtc enable.
> +	 * The WMs will be set to their proper values again when calling
> +	 * intel_update_watermarks() next.
> +	 */
> +	if (IS_VALLEYVIEW(dev))
> +		valleyview_disable_sr_watermarks(dev_priv);
>  	intel_crtc_disable_planes(crtc);
>  
>  	for_each_encoder_on_crtc(dev, crtc, encoder)
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 1840d15..01962aa 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -1306,6 +1306,13 @@ static void vlv_update_drain_latency(struct drm_device *dev)
>  	}
>  }
>  
> +void valleyview_disable_sr_watermarks(struct drm_i915_private *dev_priv)
> +{
> +	I915_WRITE(FW_BLC_SELF_VLV,
> +		   I915_READ(FW_BLC_SELF_VLV) & ~FW_CSPWRDWNEN);
> +	POSTING_READ(FW_BLC_SELF_VLV);
> +}
> +
>  #define single_plane_enabled(mask) is_power_of_2(mask)
>  
>  static void valleyview_update_wm(struct drm_crtc *crtc)
> -- 
> 1.8.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch