Re: [PATCH 1/2] drm/i915: Fix scaler init during CRTC HW state readout

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 20 Jul 2017, Imre Deak <imre.deak@intel.com> wrote:
> The scaler allocation code depends on a non-zero default value for the
> crtc scaler_id, so make sure we initialize the scaler state accordingly
> even if the crtc is off. This fixes at least an initial YUV420 modeset
> (added in a follow-up patchset by Shashank) when booting with the screen
> off: after the initial HW readout and modeset which enables the scaler a
> subsequent modeset will disable the scaler which isn't properly
> allocated. This results in a funky HW state where the pipe scaler HW
> registers can't be modified and the normally black screen is grey and
> shifted to the right or jitters.
>
> The problem was revealed by Shashank's YUV420 patchset and first
> reported by Ville.
>
> Cc: Shashank Sharma <shashank.sharma@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Chandra Konduru <chandra.konduru@intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Cc: <stable@vger.kernel.org> # 4.11.x
> Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Fixes: a1b2278e4dfc ("drm/i915: skylake panel fitting using shared scalers")
> Signed-off-by: Imre Deak <imre.deak@intel.com>
>
> ---
>
> [ Older stable versions need backporting, so that's for a follow-up ]

I thought we'd annotate cc: stable with all the kernels that need the
fix, not according to where the fix applies as-is. In this case, it
would be v4.2+, right?

BR,
Jani.



> ---
>  drivers/gpu/drm/i915/intel_display.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7774f3465fbc..8a38e64b1931 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9132,6 +9132,13 @@ static bool haswell_get_pipe_config(struct intel_crtc *crtc,
>  	u64 power_domain_mask;
>  	bool active;
>  
> +	if (INTEL_GEN(dev_priv) >= 9) {
> +		intel_crtc_init_scalers(crtc, pipe_config);
> +
> +		pipe_config->scaler_state.scaler_id = -1;
> +		pipe_config->scaler_state.scaler_users &= ~(1 << SKL_CRTC_INDEX);
> +	}
> +
>  	power_domain = POWER_DOMAIN_PIPE(crtc->pipe);
>  	if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
>  		return false;
> @@ -9160,13 +9167,6 @@ static bool haswell_get_pipe_config(struct intel_crtc *crtc,
>  	pipe_config->gamma_mode =
>  		I915_READ(GAMMA_MODE(crtc->pipe)) & GAMMA_MODE_MODE_MASK;
>  
> -	if (INTEL_GEN(dev_priv) >= 9) {
> -		intel_crtc_init_scalers(crtc, pipe_config);
> -
> -		pipe_config->scaler_state.scaler_id = -1;
> -		pipe_config->scaler_state.scaler_users &= ~(1 << SKL_CRTC_INDEX);
> -	}
> -
>  	power_domain = POWER_DOMAIN_PIPE_PANEL_FITTER(crtc->pipe);
>  	if (intel_display_power_get_if_enabled(dev_priv, power_domain)) {
>  		power_domain_mask |= BIT_ULL(power_domain);

-- 
Jani Nikula, Intel Open Source Technology Center
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