Re: [PATCH v4 07/11] drm/xe/vrsr: Enable VRSR on default VGA boot device

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 29 May 2025, Badal Nilawar <badal.nilawar@intel.com> wrote:
> The VRSR feature is to enhance the display screen refresh experience
> when the device exits from the D3Cold state. Therefore, apply the VRSR
> feature to the default VGA boot device and when a display is connected.
>
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> ---
>  drivers/gpu/drm/xe/display/xe_display.c | 22 ++++++++++++++++++++++
>  drivers/gpu/drm/xe/display/xe_display.h |  2 ++
>  drivers/gpu/drm/xe/xe_pm.c              |  5 +++++
>  3 files changed, 29 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/display/xe_display.c b/drivers/gpu/drm/xe/display/xe_display.c
> index 20c3bcd953b7..b3da88b12b35 100644
> --- a/drivers/gpu/drm/xe/display/xe_display.c
> +++ b/drivers/gpu/drm/xe/display/xe_display.c
> @@ -88,6 +88,28 @@ static void display_destroy(struct drm_device *dev, void *dummy)
>  	destroy_workqueue(xe->display.hotplug.dp_wq);
>  }
>  
> +bool xe_display_connected(struct xe_device *xe)
> +{
> +	struct drm_connector *list_connector;
> +	struct drm_connector_list_iter iter;
> +	bool ret = false;
> +
> +	mutex_lock(&xe->drm.mode_config.mutex);
> +	drm_connector_list_iter_begin(&xe->drm, &iter);
> +
> +	drm_for_each_connector_iter(list_connector, &iter) {
> +		if (list_connector->status == connector_status_connected) {
> +			ret = true;
> +			break;
> +		}
> +	}
> +
> +	drm_connector_list_iter_end(&iter);
> +	mutex_unlock(&xe->drm.mode_config.mutex);
> +
> +	return ret;
> +}
> +

Xe display/ should contain the *minimal* glue to attach i915 display to
it. It should *not* contain generic display stuff like this. At all.

The goal is for i915 display to become a dedicated kernel module. The
above should not be part of xe.ko.

BR,
Jani.

>  /**
>   * xe_display_create - create display struct
>   * @xe: XE device instance
> diff --git a/drivers/gpu/drm/xe/display/xe_display.h b/drivers/gpu/drm/xe/display/xe_display.h
> index 46e14f8dee28..c79441bccb43 100644
> --- a/drivers/gpu/drm/xe/display/xe_display.h
> +++ b/drivers/gpu/drm/xe/display/xe_display.h
> @@ -39,6 +39,7 @@ void xe_display_pm_resume(struct xe_device *xe);
>  void xe_display_pm_runtime_suspend(struct xe_device *xe);
>  void xe_display_pm_runtime_suspend_late(struct xe_device *xe);
>  void xe_display_pm_runtime_resume(struct xe_device *xe);
> +bool xe_display_connected(struct xe_device *xe);
>  
>  #else
>  
> @@ -71,5 +72,6 @@ static inline void xe_display_pm_runtime_suspend(struct xe_device *xe) {}
>  static inline void xe_display_pm_runtime_suspend_late(struct xe_device *xe) {}
>  static inline void xe_display_pm_runtime_resume(struct xe_device *xe) {}
>  
> +static inline bool xe_display_connected(struct xe_device *xe) { return false; }
>  #endif /* CONFIG_DRM_XE_DISPLAY */
>  #endif /* _XE_DISPLAY_H_ */
> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> index 278f2eeeaab6..c84b9b3f7371 100644
> --- a/drivers/gpu/drm/xe/xe_pm.c
> +++ b/drivers/gpu/drm/xe/xe_pm.c
> @@ -9,6 +9,7 @@
>  #include <linux/fault-inject.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/suspend.h>
> +#include <linux/vgaarb.h>
>  
>  #include <drm/drm_managed.h>
>  #include <drm/ttm/ttm_placement.h>
> @@ -310,6 +311,7 @@ static int pci_acpi_aux_power_setup(struct xe_device *xe)
>  
>  static void xe_pm_vrsr_init(struct xe_device *xe)
>  {
> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>  	int ret;
>  
>  	/* Check if platform support D3Cold VRSR */
> @@ -319,6 +321,9 @@ static void xe_pm_vrsr_init(struct xe_device *xe)
>  	if (!xe_pm_vrsr_capable(xe))
>  		return;
>  
> +	if (pdev != vga_default_device() || !xe_display_connected(xe))
> +		return;
> +
>  	/*
>  	 * If the VRSR initialization fails, the device will proceed with the regular
>  	 * D3Cold flow

-- 
Jani Nikula, Intel