linux-kernel - Re: [Intel-gfx] [PATCH] drm/i915: disable non-sequential pfits on ivb/hsw

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Message-ID: <87mvs8y3gu.fsf@intel.com>
Date:	Thu, 14 Jan 2016 10:23:13 +0200
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	Chris Bainbridge <chris.bainbridge@...il.com>,
	daniel.vetter@...el.com
Cc:	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [Intel-gfx] [PATCH] drm/i915: disable non-sequential pfits on	ivb/hsw

On Wed, 13 Jan 2016, Chris Bainbridge <chris.bainbridge@...il.com> wrote:
> The existing code assumes a sequential mapping of panel fitters to pipes
> (pfit0-pipeA, pfit1-pipeB, pfit2-pipeC), but boot firmware can
> arbitrarily assign any pipe to a pfit on IVB hardware e.g. Macbook UEFI
> uses pfit 0 and pipe C for eDP1 when the firmware boots in a non-16:10
> resolution (the last-used resolution is stored in NVRAM by OS X so the
> firmware can immediately restore it at boot). When this happens, the
> display will appear letterboxed due to incorrect aspect ratio and
> attempting to switch to alternative resolutions will fail. Fix this by
> disabling any panel fitters which have been non-sequentially assigned at
> boot time.
>
> Link: https://bugs.freedesktop.org/show_bug.cgi?id=93523

s/Link/Bugzilla/

> Signed-off-by: Chris Bainbridge <chris.bainbridge@...il.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 26 ++++++++++++++++++--------
>  1 file changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 32cf97346978..9e588139a2dd 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9170,6 +9170,24 @@ static void ironlake_get_pfit_config(struct intel_crtc *crtc,
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	uint32_t tmp;
> +	int pipe;
> +
> +	/*
> +	 * PF_CTL assumes panel fitter 0 is on pipe A, panel fitter 1 is on
> +	 * pipe B, and panel fitter 2 is on pipe C, but firmware can init IVB
> +	 * panel fitters to any arbitrary pipe (Macbook UEFI uses pfit 0 for
> +	 * pipe C), so find and disable any other mappings.
> +	 */
> +	for (pipe = 0; pipe < INTEL_INFO(dev)->num_pipes; pipe++) {
> +		tmp = I915_READ(PF_CTL(pipe));
> +		if (IS_GEN7(dev) && (tmp & PF_ENABLE) &&
> +		    PF_PIPE_SEL_IVB(pipe) != (tmp & PF_PIPE_SEL_MASK_IVB)) {
> +			DRM_DEBUG_KMS("disabling initial panel fitter\n");
> +			I915_WRITE(PF_CTL(pipe), 0);
> +			I915_WRITE(PF_WIN_POS(pipe), 0);
> +			I915_WRITE(PF_WIN_SZ(pipe), 0);
> +		}
> +	}
>  
>  	tmp = I915_READ(PF_CTL(crtc->pipe));
>  
> @@ -9177,14 +9195,6 @@ static void ironlake_get_pfit_config(struct intel_crtc *crtc,
>  		pipe_config->pch_pfit.enabled = true;
>  		pipe_config->pch_pfit.pos = I915_READ(PF_WIN_POS(crtc->pipe));
>  		pipe_config->pch_pfit.size = I915_READ(PF_WIN_SZ(crtc->pipe));
> -
> -		/* We currently do not free assignements of panel fitters on
> -		 * ivb/hsw (since we don't use the higher upscaling modes which
> -		 * differentiates them) so just WARN about this case for now. */
> -		if (IS_GEN7(dev)) {
> -			WARN_ON((tmp & PF_PIPE_SEL_MASK_IVB) !=
> -				PF_PIPE_SEL_IVB(crtc->pipe));
> -		}
>  	}
>  }

-- 
Jani Nikula, Intel Open Source Technology Center