Re: [PATCH 1/3] drm/i915: Don't check modeset state in the hw state force restore path

[Matt Roper <matthew.d.roper@intel.com>]

On Fri, Jun 12, 2015 at 10:19:40AM +0300, Ander Conselvan de Oliveira wrote:
> Since the force restore logic will restore the CRTCs state one at a
> time, it is possible that the state will be inconsistent until the whole
> operation finishes. A call to intel_modeset_check_state() is done once
> it's over, so don't check the state multiple times in between. This
> regression was introduced in:
> 
> commit 7f27126ea3db6ade886f18fd39caf0ff0cd1d37f
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Wed Nov 5 14:26:06 2014 -0800
> 
>     drm/i915: factor out compute_config from __intel_set_mode v3
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94431
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 4e3f302..6ef57e6 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -87,7 +87,8 @@ static void ironlake_pch_clock_get(struct intel_crtc *crtc,
>  				   struct intel_crtc_state *pipe_config);
>  
>  static int intel_set_mode(struct drm_crtc *crtc,
> -			  struct drm_atomic_state *state);
> +			  struct drm_atomic_state *state,
> +			  bool check);
>  static int intel_framebuffer_init(struct drm_device *dev,
>  				  struct intel_framebuffer *ifb,
>  				  struct drm_mode_fb_cmd2 *mode_cmd,
> @@ -10096,7 +10097,7 @@ retry:
>  
>  	drm_mode_copy(&crtc_state->base.mode, mode);
>  
> -	if (intel_set_mode(crtc, state)) {
> +	if (intel_set_mode(crtc, state, true)) {
>  		DRM_DEBUG_KMS("failed to set mode on load-detect pipe\n");
>  		if (old->release_fb)
>  			old->release_fb->funcs->destroy(old->release_fb);
> @@ -10170,7 +10171,7 @@ void intel_release_load_detect_pipe(struct drm_connector *connector,
>  		if (ret)
>  			goto fail;
>  
> -		ret = intel_set_mode(crtc, state);
> +		ret = intel_set_mode(crtc, state, true);
>  		if (ret)
>  			goto fail;
>  
> @@ -12646,20 +12647,22 @@ static int __intel_set_mode(struct drm_crtc *modeset_crtc,
>  }
>  
>  static int intel_set_mode_with_config(struct drm_crtc *crtc,
> -				      struct intel_crtc_state *pipe_config)
> +				      struct intel_crtc_state *pipe_config,
> +				      bool check)

This parameter just controls whether you check the state or not in this
patch, but in patch #2 it also starts having more of a behavioral impact
(i.e., "don't updated staged output configuration").  I wonder if
picking a different name for this parameter would help avoid any
confusion?

Otherwise, this patch looks good:
   Reviewed-by: Matt Roper <matthew.d.roper@intel.com>

Off-topic, but speaking of 'check' I wonder whether we should also
rename the intel_modeset_check_state function and related functions at
some point in the future.  Every time I see that name in the code it
bothers me because I expect it to be related to atomic check (i.e.,
something that runs before we touch hardware) rather than confirming
that hardware programming was successful.  It feels more like an
assert/confirm/verify function to me.


Matt

>  {
>  	int ret;
>  
>  	ret = __intel_set_mode(crtc, pipe_config);
>  
> -	if (ret == 0)
> +	if (ret == 0 && check)
>  		intel_modeset_check_state(crtc->dev);
>  
>  	return ret;
>  }
>  
>  static int intel_set_mode(struct drm_crtc *crtc,
> -			  struct drm_atomic_state *state)
> +			  struct drm_atomic_state *state,
> +			  bool check)
>  {
>  	struct intel_crtc_state *pipe_config;
>  	int ret = 0;
> @@ -12670,7 +12673,7 @@ static int intel_set_mode(struct drm_crtc *crtc,
>  		goto out;
>  	}
>  
> -	ret = intel_set_mode_with_config(crtc, pipe_config);
> +	ret = intel_set_mode_with_config(crtc, pipe_config, check);
>  	if (ret)
>  		goto out;
>  
> @@ -12747,7 +12750,7 @@ void intel_crtc_restore_mode(struct drm_crtc *crtc)
>  	intel_modeset_setup_plane_state(state, crtc, &crtc->mode,
>  					crtc->primary->fb, crtc->x, crtc->y);
>  
> -	ret = intel_set_mode(crtc, state);
> +	ret = intel_set_mode(crtc, state, false);
>  	if (ret)
>  		drm_atomic_state_free(state);
>  }
> @@ -12947,7 +12950,7 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
>  
>  	primary_plane_was_visible = primary_plane_visible(set->crtc);
>  
> -	ret = intel_set_mode_with_config(set->crtc, pipe_config);
> +	ret = intel_set_mode_with_config(set->crtc, pipe_config, true);
>  
>  	if (ret == 0 &&
>  	    pipe_config->base.enable &&
> -- 
> 2.1.0
> 
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-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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