Re: [PATCH 5/5] drm/vblank: Lock down vblank->hwmode more

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 5/5] drm/vblank: Lock down vblank->hwmode more
Date: Wed, 3 May 2017 17:09:08 +0300	[thread overview]
Message-ID: <20170503140908.GL12629@intel.com> (raw)
In-Reply-To: <20170503072638.16826-6-daniel.vetter@ffwll.ch>

On Wed, May 03, 2017 at 09:26:38AM +0200, Daniel Vetter wrote:
> In the previous patch we've implemented hwmode tracking a la i915 for
> the vblank timestamp calculations. But that was just the basic
> semantics, i915 has some nice sanity checks to make sure we keep
> getting this right. Move them over too.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/gpu/drm/drm_irq.c            |  8 +++++++-
>  drivers/gpu/drm/i915/i915_irq.c      | 10 ++++++----
>  drivers/gpu/drm/i915/intel_display.c | 11 ++---------
>  3 files changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index 89f0928b042a..942183a2aa3c 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -775,8 +775,10 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
>  	/* If mode timing undefined, just return as no-op:
>  	 * Happens during initial modesetting of a crtc.
>  	 */
> -	if (mode->crtc_clock == 0) {
> +	if (WARN_ON(mode->crtc_clock == 0)) {
>  		DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);
> +		WARN_ON(drm_drv_uses_atomic_modeset(dev));

I would make these _ONCE() otherwise the machine might end up
practically dead.

> +
>  		return false;
>  	}
>  
> @@ -1338,6 +1340,10 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc)
>  		send_vblank_event(dev, e, seq, &now);
>  	}
>  	spin_unlock_irqrestore(&dev->event_lock, irqflags);
> +
> +	/* Will be reset by the modeset helpers when re-enabling the crtc by
> +	 * calling drm_calc_timestamping_constants(). */
> +	vblank->hwmode.crtc_clock = 0;
>  }
>  EXPORT_SYMBOL(drm_crtc_vblank_off);

Shouldn't we do this in drm_crtc_vblank_reset() as well?

Hmm. Except we call that after drm_calc_timestamping_constants(). I
guess we should be able to move the reset() into
intel_modeset_readout_hw_state(). And possibly move the vblank_on()
call as well?

>  
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 837e5bc2019a..ff18b3fc00d2 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -720,9 +720,7 @@ static u32 i915_get_vblank_counter(struct drm_device *dev, unsigned int pipe)
>  	struct drm_i915_private *dev_priv = to_i915(dev);
>  	i915_reg_t high_frame, low_frame;
>  	u32 high1, high2, low, pixel, vbl_start, hsync_start, htotal;
> -	struct intel_crtc *intel_crtc = intel_get_crtc_for_pipe(dev_priv,
> -								pipe);
> -	const struct drm_display_mode *mode = &intel_crtc->base.hwmode;
> +	const struct drm_display_mode *mode = &dev->vblank[pipe].hwmode;
>  	unsigned long irqflags;
>  
>  	htotal = mode->crtc_htotal;
> @@ -779,13 +777,17 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
>  {
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = to_i915(dev);
> -	const struct drm_display_mode *mode = &crtc->base.hwmode;
> +	const struct drm_display_mode *mode;
> +	struct drm_vblank_crtc *vblank;
>  	enum pipe pipe = crtc->pipe;
>  	int position, vtotal;
>  
>  	if (!crtc->active)
>  		return -1;
>  
> +	vblank = &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)];
> +	mode = &vblank->hwmode;
> +
>  	vtotal = mode->crtc_vtotal;
>  	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
>  		vtotal /= 2;
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 85b9e2f521a0..a190973daeee 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -11443,12 +11443,6 @@ intel_modeset_update_crtc_state(struct drm_atomic_state *state)
>  	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
>  		to_intel_crtc(crtc)->config = to_intel_crtc_state(new_crtc_state);
>  
> -		/* Update hwmode for vblank functions */
> -		if (new_crtc_state->active)
> -			crtc->hwmode = new_crtc_state->adjusted_mode;
> -		else
> -			crtc->hwmode.crtc_clock = 0;
> -
>  		/*
>  		 * Update legacy state to satisfy fbc code. This can
>  		 * be removed when fbc uses the atomic state.
> @@ -15425,8 +15419,6 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
>  			to_intel_crtc_state(crtc->base.state);
>  		int pixclk = 0;
>  
> -		crtc->base.hwmode = crtc_state->base.adjusted_mode;
> -
>  		memset(&crtc->base.mode, 0, sizeof(crtc->base.mode));
>  		if (crtc_state->base.active) {
>  			intel_mode_from_pipe_config(&crtc->base.mode, crtc_state);
> @@ -15456,7 +15448,8 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
>  			if (IS_BROADWELL(dev_priv) && crtc_state->ips_enabled)
>  				pixclk = DIV_ROUND_UP(pixclk * 100, 95);
>  
> -			drm_calc_timestamping_constants(&crtc->base, &crtc->base.hwmode);
> +			drm_calc_timestamping_constants(&crtc->base,
> +							&crtc_state->base.adjusted_mode);
>  			update_scanline_offset(crtc);
>  		}
>  
> -- 
> 2.11.0

-- 
Ville Syrjälä
Intel OTC
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