Re: [PATCH v3 24/25] drm/i915: propagate the error code from runtime PM callbacks

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

On Tue, Apr 15, 2014 at 04:39:45PM +0300, Imre Deak wrote:
> Atm, none of the RPM callbacks can fail, but the next patch adding
> RPM support for VLV changes this, so prepare for it.
> 
> In case one of these callbacks return error RPM will get permanently
> disabled until the error is explicitly cleared. In the future we could
> add support for re-enabling it, for example after resetting the HW, but
> for now - hopefully - we can live with the simpler solution.
> 
> v2:
> - propagate the error from the resume callbacks too (Paulo)
> v3:
> - fix rebase fail typo around IS_GEN6() check in intel_runtime_suspend()
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 57 ++++++++++++++++++++++++++++++-----------
>  1 file changed, 42 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 845e1e1..aeb7dec 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -888,21 +888,27 @@ static int i915_pm_poweroff(struct device *dev)
>  	return i915_drm_freeze(drm_dev);
>  }
>  
> -static void hsw_runtime_suspend(struct drm_i915_private *dev_priv)
> +static int hsw_runtime_suspend(struct drm_i915_private *dev_priv)
>  {
>  	hsw_enable_pc8(dev_priv);
> +
> +	return 0;
>  }
>  
> -static void snb_runtime_resume(struct drm_i915_private *dev_priv)
> +static int snb_runtime_resume(struct drm_i915_private *dev_priv)
>  {
>  	struct drm_device *dev = dev_priv->dev;
>  
>  	intel_init_pch_refclk(dev);
> +
> +	return 0;
>  }
>  
> -static void hsw_runtime_resume(struct drm_i915_private *dev_priv)
> +static int hsw_runtime_resume(struct drm_i915_private *dev_priv)
>  {
>  	hsw_disable_pc8(dev_priv);
> +
> +	return 0;
>  }
>  
>  int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on)
> @@ -947,6 +953,7 @@ static int intel_runtime_suspend(struct device *device)
>  	struct pci_dev *pdev = to_pci_dev(device);
>  	struct drm_device *dev = pci_get_drvdata(pdev);
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +	int ret;
>  
>  	if (WARN_ON_ONCE(!(dev_priv->rps.enabled && intel_enable_rc6(dev))))
>  		return -ENODEV;
> @@ -959,12 +966,21 @@ static int intel_runtime_suspend(struct device *device)
>  	intel_runtime_pm_disable_interrupts(dev);
>  	cancel_work_sync(&dev_priv->rps.work);
>  
> -	if (IS_GEN6(dev))
> -		;
> -	else if (IS_HASWELL(dev) || IS_BROADWELL(dev))
> -		hsw_runtime_suspend(dev_priv);
> -	else
> +	if (IS_GEN6(dev)) {
> +		ret = 0;
> +	} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
> +		ret = hsw_runtime_suspend(dev_priv);
> +	} else {
> +		ret = -ENODEV;
>  		WARN_ON(1);
> +	}
> +
> +	if (ret) {
> +		DRM_ERROR("Runtime suspend failed, disabling it (%d)\n", ret);
> +		intel_runtime_pm_restore_interrupts(dev);
> +
> +		return ret;
> +	}
>  
>  	i915_gem_release_all_mmaps(dev_priv);

Not strictly related to this patch, but shouldn't we nuke the mmaps before
calling the platform specific runtime suspend function?

This patch itself looks ok to me:
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

>  
> @@ -989,6 +1005,7 @@ static int intel_runtime_resume(struct device *device)
>  	struct pci_dev *pdev = to_pci_dev(device);
>  	struct drm_device *dev = pci_get_drvdata(pdev);
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +	int ret;
>  
>  	WARN_ON(!HAS_RUNTIME_PM(dev));
>  
> @@ -997,21 +1014,31 @@ static int intel_runtime_resume(struct device *device)
>  	intel_opregion_notify_adapter(dev, PCI_D0);
>  	dev_priv->pm.suspended = false;
>  
> -	if (IS_GEN6(dev))
> -		snb_runtime_resume(dev_priv);
> -	else if (IS_HASWELL(dev) || IS_BROADWELL(dev))
> -		hsw_runtime_resume(dev_priv);
> -	else
> +	if (IS_GEN6(dev)) {
> +		ret = snb_runtime_resume(dev_priv);
> +	} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
> +		ret = hsw_runtime_resume(dev_priv);
> +	} else {
>  		WARN_ON(1);
> +		ret = -ENODEV;
> +	}
>  
> +	/*
> +	 * No point of rolling back things in case of an error, as the best
> +	 * we can do is to hope that things will still work (and disable RPM).
> +	 */
>  	i915_gem_init_swizzling(dev);
>  	gen6_update_ring_freq(dev);
>  	intel_reset_gt_powersave(dev);
>  
>  	intel_runtime_pm_restore_interrupts(dev);
>  
> -	DRM_DEBUG_KMS("Device resumed\n");
> -	return 0;
> +	if (ret)
> +		DRM_ERROR("Runtime resume failed, disabling it (%d)\n", ret);
> +	else
> +		DRM_DEBUG_KMS("Device resumed\n");
> +
> +	return ret;
>  }
>  
>  static const struct dev_pm_ops i915_pm_ops = {
> -- 
> 1.8.4
> 
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-- 
Ville Syrjälä
Intel OTC