[Intel-gfx] [PATCH] drm/i915: Detect virtual south bridge

[Jesse Barnes]

On 08/28/2015 05:10 AM, robert.beckett at intel.com wrote:
> From: Robert Beckett <robert.beckett at intel.com>
> 
> Virtualized systems often use a virtual P2X4 south bridge.
> Detect this in intel_detect_pch and make a best guess as to which PCH
> we should be using.
> 
> This was seen on vmware esxi hypervisor. When passing the graphics device
> through to a guest, it can not pass through the PCH. Instead it simulates
> a P2X4 southbridge.
> 
> Signed-off-by: Robert Beckett <robert.beckett at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c |   30 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_drv.h |    1 +
>  2 files changed, 31 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index ce3bd0c..8e158b3 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -443,6 +443,34 @@ static const struct pci_device_id pciidlist[] = {		/* aka */
>  
>  MODULE_DEVICE_TABLE(pci, pciidlist);
>  
> +static enum intel_pch intel_virt_detect_pch(struct drm_device *dev)
> +{
> +	enum intel_pch ret = PCH_NOP;
> +
> +	/*
> +	 * In a virtualized passthrough environment we can be in a
> +	 * setup where the ISA bridge is not able to be passed through.
> +	 * In this case, a south bridge can be emulated and we have to
> +	 * make an educated guess as to which PCH is really there.
> +	 */
> +
> +	if (IS_GEN5(dev)) {
> +		ret = PCH_IBX;
> +		DRM_DEBUG_KMS("Assuming Ibex Peak PCH\n");
> +	} else if (IS_GEN6(dev) || IS_IVYBRIDGE(dev)) {
> +		ret = PCH_CPT;
> +		DRM_DEBUG_KMS("Assuming CouarPoint PCH\n");
> +	} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
> +		ret = PCH_LPT;
> +		DRM_DEBUG_KMS("Assuming LynxPoint PCH\n");
> +	} else if (IS_SKYLAKE(dev)) {
> +		ret = PCH_SPT;
> +		DRM_DEBUG_KMS("Assuming SunrisePoint PCH\n");
> +	}
> +
> +	return ret;
> +}
> +
>  void intel_detect_pch(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -503,6 +531,8 @@ void intel_detect_pch(struct drm_device *dev)
>  				dev_priv->pch_type = PCH_SPT;
>  				DRM_DEBUG_KMS("Found SunrisePoint LP PCH\n");
>  				WARN_ON(!IS_SKYLAKE(dev));
> +			} else if (id == INTEL_PCH_P2X_DEVICE_ID_TYPE) {
> +				dev_priv->pch_type = intel_virt_detect_pch(dev);
>  			} else
>  				continue;
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 8c93845..6eb0230 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2584,6 +2584,7 @@ struct drm_i915_cmd_table {
>  #define INTEL_PCH_LPT_LP_DEVICE_ID_TYPE		0x9c00
>  #define INTEL_PCH_SPT_DEVICE_ID_TYPE		0xA100
>  #define INTEL_PCH_SPT_LP_DEVICE_ID_TYPE		0x9D00
> +#define INTEL_PCH_P2X_DEVICE_ID_TYPE		0x7100
>  
>  #define INTEL_PCH_TYPE(dev) (__I915__(dev)->pch_type)
>  #define HAS_PCH_SPT(dev) (INTEL_PCH_TYPE(dev) == PCH_SPT)
> 

Assuming Kevin is ok with this:
Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>