[Intel-xe] [PATCH v4] drm/xe/pm: Disable PM on unbounded pcie parent bridge

[Rodrigo Vivi]

On Wed, May 24, 2023 at 02:36:53PM +0530, Anshuman Gupta wrote:
> Intel Discrete GFX cards gfx may have multiple PCIe endpoints,
> they connects to root port via pcie upstream switch port(USP)
> and virtual pcie switch port(VSP), sometimes VSP pcie devices
> doesn't bind to pcieport driver. Without pcieport driver, pcie PM
> comes without any warranty and with unbounded VSP gfx card won't
> transition to low power pcie Device and Link states therefore
> assert drm_warn on unbounded VSP and disable xe driver
> PM support.
> 
> v2:
> - Disable Xe PCI PM support. [Rodrigo]
> v3:
> - Changed subject and Rebase.
> v4:
> - %s/xe_pci_unbounded_bridge_disable_pm/xe_assert_on_unbounded_bridge.
>   [Rodrigo]
> - Use device_set_pm_not_required() instead of dev_pm_ops NULL assignment.
> 
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

(we should probably do something very similar on i915 for dg2/dg1 no?!)

> ---
>  drivers/gpu/drm/xe/xe_pci.c |  1 +
>  drivers/gpu/drm/xe/xe_pm.c  | 14 ++++++++++++++
>  drivers/gpu/drm/xe/xe_pm.h  |  1 +
>  3 files changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 2d0d50dcd396..45bd23b879b9 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -636,6 +636,7 @@ static int xe_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	if (IS_ERR(xe))
>  		return PTR_ERR(xe);
>  
> +	xe_pm_assert_unbounded_bridge(xe);
>  	subplatform_desc = find_subplatform(xe, desc);
>  
>  	err = xe_info_init(xe, desc, subplatform_desc);
> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> index b7b57f10ba25..c7901f379aee 100644
> --- a/drivers/gpu/drm/xe/xe_pm.c
> +++ b/drivers/gpu/drm/xe/xe_pm.c
> @@ -225,3 +225,17 @@ int xe_pm_runtime_get_if_active(struct xe_device *xe)
>  	WARN_ON(pm_runtime_suspended(xe->drm.dev));
>  	return pm_runtime_get_if_active(xe->drm.dev, true);
>  }
> +
> +void xe_pm_assert_unbounded_bridge(struct xe_device *xe)
> +{
> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> +	struct pci_dev *bridge = pci_upstream_bridge(pdev);
> +
> +	if (!bridge)
> +		return;
> +
> +	if (!bridge->driver) {
> +		drm_warn(&xe->drm, "unbounded parent pci bridge, device won't support any PM support.\n");
> +		device_set_pm_not_required(&pdev->dev);
> +	}
> +}
> diff --git a/drivers/gpu/drm/xe/xe_pm.h b/drivers/gpu/drm/xe/xe_pm.h
> index 6a885585f653..8418ee6faac5 100644
> --- a/drivers/gpu/drm/xe/xe_pm.h
> +++ b/drivers/gpu/drm/xe/xe_pm.h
> @@ -21,5 +21,6 @@ int xe_pm_runtime_get(struct xe_device *xe);
>  int xe_pm_runtime_put(struct xe_device *xe);
>  bool xe_pm_runtime_resume_if_suspended(struct xe_device *xe);
>  int xe_pm_runtime_get_if_active(struct xe_device *xe);
> +void xe_pm_assert_unbounded_bridge(struct xe_device *xe);
>  
>  #endif
> -- 
> 2.38.0
>