[Intel-gfx] [PATCH] drm/i915/dg1: Disable D3 for gfx's VSP

[Rodrigo Vivi]

On Wed, Jul 20, 2022 at 06:51:37PM +0530, Anshuman Gupta wrote:
> When DG1 gfx pci endpoint's parent upstream bridge (VSP) enters
> to D3, any direct memory read from lmem returns with 0xff.
> DG1 requires i915 driven runtime resume in order to read properly
> from lmem, DG1 is unable to wakeup from local memory reads.
> This may breaks using mmap() with lmem object on DG1 as it
> relies on mercy of i915 driven runtime resume.

why our disable at root_port not working to block this case?
If the root power is not at D3Cold our power shouldn't be cut
and our memory should be there.

> 
> Let's not break using mmap() for lmem object on DG1.
> Using pci_d3cold_disable(i915) accordingly to disable D3 for
> upstream bridge.
> 
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6331
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 6ed5786bcd29..671009fd351a 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -559,6 +559,7 @@ void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)
>  	struct drm_i915_private *i915 = container_of(rpm,
>  						     struct drm_i915_private,
>  						     runtime_pm);
> +	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
>  	struct device *kdev = rpm->kdev;
>  
>  	/*
> @@ -574,6 +575,9 @@ void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)
>  	pm_runtime_set_autosuspend_delay(kdev, 10000); /* 10s */
>  	pm_runtime_mark_last_busy(kdev);
>  
> +	if (IS_DG1(i915))
> +		pci_d3cold_disable(pdev);
> +
>  	/*
>  	 * Take a permanent reference to disable the RPM functionality and drop
>  	 * it only when unloading the driver. Use the low level get/put helpers,
> @@ -607,12 +611,16 @@ void intel_runtime_pm_disable(struct intel_runtime_pm *rpm)
>  	struct drm_i915_private *i915 = container_of(rpm,
>  						     struct drm_i915_private,
>  						     runtime_pm);
> +	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
>  	struct device *kdev = rpm->kdev;
>  
>  	/* Transfer rpm ownership back to core */
>  	drm_WARN(&i915->drm, pm_runtime_get_sync(kdev) < 0,
>  		 "Failed to pass rpm ownership back to core\n");
>  
> +	if (IS_DG1(i915))
> +		pci_d3cold_enable(pdev);
> +
>  	pm_runtime_dont_use_autosuspend(kdev);
>  
>  	if (!rpm->available)
> -- 
> 2.26.2
>