Re: [PATCH v2] drm/i915: Restore interrupt enabling after a reset

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Feb 18, 2019 at 03:31:06PM +0000, Chris Wilson wrote:
> At least on i965g and i965gm, performing a device reset clobbers the IER
> resulting in loss of interrupts thereafter. So, run the irq_postinstall
> hook to restore them.
> 
> v2: Ville pointed out that he already attempted to solve this problem by
> reinstall the interrupts in intel_reset_finish() (part of the display
> handling around reset). However, reinstalling the irq clobbers the
> i915->irq_mask which we need for handling MI_USER_INTERRUPTS, and does
> so too late to handle any interrupts generating from resuming the rings.
> The simple solution to both is to pull the interrupt reenabling from
> afterwards to around the device reset.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reset.c    | 6 ++++++
>  drivers/gpu/drm/i915/intel_display.c | 3 ---
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
> index 1911e00d2581..4df4c674223d 100644
> --- a/drivers/gpu/drm/i915/i915_reset.c
> +++ b/drivers/gpu/drm/i915/i915_reset.c
> @@ -995,11 +995,17 @@ void i915_reset(struct drm_i915_private *i915,
>  		goto error;
>  	}
>  
> +	if (INTEL_INFO(i915)->gpu_reset_clobbers_display)
> +		intel_runtime_pm_disable_interrupts(i915);
> +
>  	if (do_reset(i915, stalled_mask)) {
>  		dev_err(i915->drm.dev, "Failed to reset chip\n");
>  		goto taint;
>  	}
>  
> +	if (INTEL_INFO(i915)->gpu_reset_clobbers_display)
> +		intel_runtime_pm_enable_interrupts(i915);
> +

Looks quite sensible to me.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

>  	intel_overlay_reset(i915);
>  
>  	/*
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index afa21daaae51..3b4a6eeb4573 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3931,9 +3931,6 @@ void intel_finish_reset(struct drm_i915_private *dev_priv)
>  		 * The display has been reset as well,
>  		 * so need a full re-initialization.
>  		 */
> -		intel_runtime_pm_disable_interrupts(dev_priv);
> -		intel_runtime_pm_enable_interrupts(dev_priv);
> -
>  		intel_pps_unlock_regs_wa(dev_priv);
>  		intel_modeset_init_hw(dev);
>  		intel_init_clock_gating(dev_priv);
> -- 
> 2.20.1

-- 
Ville Syrjälä
Intel
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