Re: [Intel-gfx] [PATCH] drm/i915: disable cpt phase pointer fdi rx workaround

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Sat,  8 Dec 2012 12:58:33 +0100
Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> We've originally added this in
> 
> commit 291427f5fdadec6e4be2924172e83588880e1539
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Fri Jul 29 12:42:37 2011 -0700
> 
>     drm/i915: apply phase pointer override on SNB+ too
> 
> and then copy-pasted it over to ivb/ppt. The w/a was originally added
> for ilk/ibx in
> 
> commit 5b2adf897146edeac6a1e438fb67b5a53dbbdf34
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Thu Oct 7 16:01:15 2010 -0700
> 
>     drm/i915: add Ironlake clock gating workaround for FDI link training
> 
> and fixed up a bit in
> 
> commit 6f06ce184c765fd8d50669a8d12fdd566c920859
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Tue Jan 4 15:09:38 2011 -0800
> 
>     drm/i915: set phase sync pointer override enable before setting phase sync pointer
> 
> It turns out that this w/a isn't actually required on cpt/ppt and
> positively harmful on ivb/ppt when using fdi B/C links - it results in
> a black screen occasionally, with seemingfully everything working as
> it should. The only failure indication I've found in the hw is that
> eventually (but not right after the modeset completes) a pipe underrun
> is signalled.
> 
> Big thanks to Arthur Runyan for all the ideas for registers to check
> and changes to test, otherwise I couldn't ever have tracked this down!
> 
> Cc: "Runyan, Arthur J" <arthur.j.runyan@intel.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 29 -----------------------------
>  1 file changed, 29 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index b29259a..6929104 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2335,18 +2335,6 @@ static void intel_fdi_normal_train(struct drm_crtc *crtc)
>  			   FDI_FE_ERRC_ENABLE);
>  }
>  
> -static void cpt_phase_pointer_enable(struct drm_device *dev, int pipe)
> -{
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -	u32 flags = I915_READ(SOUTH_CHICKEN1);
> -
> -	flags |= FDI_PHASE_SYNC_OVR(pipe);
> -	I915_WRITE(SOUTH_CHICKEN1, flags); /* once to unlock... */
> -	flags |= FDI_PHASE_SYNC_EN(pipe);
> -	I915_WRITE(SOUTH_CHICKEN1, flags); /* then again to enable */
> -	POSTING_READ(SOUTH_CHICKEN1);
> -}
> -
>  static void ivb_modeset_global_resources(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -2521,8 +2509,6 @@ static void gen6_fdi_link_train(struct drm_crtc *crtc)
>  	POSTING_READ(reg);
>  	udelay(150);
>  
> -	cpt_phase_pointer_enable(dev, pipe);
> -
>  	for (i = 0; i < 4; i++) {
>  		reg = FDI_TX_CTL(pipe);
>  		temp = I915_READ(reg);
> @@ -2655,8 +2641,6 @@ static void ivb_manual_fdi_link_train(struct drm_crtc *crtc)
>  	POSTING_READ(reg);
>  	udelay(150);
>  
> -	cpt_phase_pointer_enable(dev, pipe);
> -
>  	for (i = 0; i < 4; i++) {
>  		reg = FDI_TX_CTL(pipe);
>  		temp = I915_READ(reg);
> @@ -2791,17 +2775,6 @@ static void ironlake_fdi_pll_disable(struct intel_crtc *intel_crtc)
>  	udelay(100);
>  }
>  
> -static void cpt_phase_pointer_disable(struct drm_device *dev, int pipe)
> -{
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -	u32 flags = I915_READ(SOUTH_CHICKEN1);
> -
> -	flags &= ~(FDI_PHASE_SYNC_EN(pipe));
> -	I915_WRITE(SOUTH_CHICKEN1, flags); /* once to disable... */
> -	flags &= ~(FDI_PHASE_SYNC_OVR(pipe));
> -	I915_WRITE(SOUTH_CHICKEN1, flags); /* then again to lock */
> -	POSTING_READ(SOUTH_CHICKEN1);
> -}
>  static void ironlake_fdi_disable(struct drm_crtc *crtc)
>  {
>  	struct drm_device *dev = crtc->dev;
> @@ -2828,8 +2801,6 @@ static void ironlake_fdi_disable(struct drm_crtc *crtc)
>  	/* Ironlake workaround, disable clock pointer after downing FDI */
>  	if (HAS_PCH_IBX(dev)) {
>  		I915_WRITE(FDI_RX_CHICKEN(pipe), FDI_RX_PHASE_SYNC_POINTER_OVR);
> -	} else if (HAS_PCH_CPT(dev)) {
> -		cpt_phase_pointer_disable(dev, pipe);
>  	}
>  
>  	/* still set train pattern 1 */

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center