Re: [PATCH 21/58] drm/i915: WARN when trying to enabled an unused crtc

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Sun, 19 Aug 2012 21:12:38 +0200
Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> This is the first tiny step towards cross-checking the entire modeset
> state machine with WARNs. A crtc can only be enabled when it's
> actually in use, i.e. crtc->active imlies crtc->enabled.
> 
> Unfortunately we can't (yet) check this when disabling the crtc,
> because the crtc helpers are a bit slopy with updating state and
> unconditionally update crtc->enabled before changing the hw state.
> 
> Fixing that requires quite some more work.
> 
> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/intel_display.c |  4 ++++
>  drivers/gpu/drm/i915/intel_drv.h     | 10 +++++++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index ca17010..5ab8694 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3215,6 +3215,8 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
>  	u32 temp;
>  	bool is_pch_port;
>  
> +	WARN_ON(!crtc->enabled);
> +
>  	/* XXX: For compatability with the crtc helper code, call the encoder's
>  	 * enable function unconditionally for now. */
>  	if (intel_crtc->active)
> @@ -3391,6 +3393,8 @@ static void i9xx_crtc_enable(struct drm_crtc *crtc)
>  	int pipe = intel_crtc->pipe;
>  	int plane = intel_crtc->plane;
>  
> +	WARN_ON(!crtc->enabled);
> +
>  	/* XXX: For compatability with the crtc helper code, call the encoder's
>  	 * enable function unconditionally for now. */
>  	if (intel_crtc->active)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 673e8d4..36991de 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -158,7 +158,15 @@ struct intel_crtc {
>  	enum plane plane;
>  	u8 lut_r[256], lut_g[256], lut_b[256];
>  	int dpms_mode;
> -	bool active; /* is the crtc on? independent of the dpms mode */
> +	/*
> +	 * Whether the crtc and the connected output pipeline is active. Implies
> +	 * that crtc->enabled is set, i.e. the current mode configuration has
> +	 * some outputs connected to this crtc.
> +	 *
> +	 * Atm crtc->enabled is unconditionally updated _before_ the hw state is
> +	 * changed, hence we can only check this when enabling the crtc.
> +	 */
> +	bool active;
>  	bool primary_disabled; /* is the crtc obscured by a plane? */
>  	bool lowfreq_avail;
>  	struct intel_overlay *overlay;

Looking forward to seeing this cleaned up.

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

-- 
Jesse Barnes, Intel Open Source Technology Center