Re: [PATCH v2 6/9] drm/xe/pci: Add upstream switch port lookup helper

["Mallesh, Koujalagi" <mallesh.koujalagi@intel.com>]

On 26-10-2026 11:35 am, Riana Tauro wrote:
> Move the USP lookup logic out of RAS code and into the PCI
nit: s/into the PCI layer/into the xe driver's PCI layer
> layer so it can be reused by other callers.
>
> No functional change.
>
> Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Reviewed-by: Mallesh Koujalagi <mallesh.koujalagi@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_pci.c | 23 +++++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_pci.h |  1 +
>   drivers/gpu/drm/xe/xe_ras.c | 19 ++-----------------
>   3 files changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 0c13eb901aa7..a9b8e65dff07 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -1521,6 +1521,29 @@ struct xe_device *xe_pci_to_pf_device(struct pci_dev *pdev)
>   	return to_xe_device(drm);
>   }
>   
> +/**
> + * xe_pci_get_usp_dev() - Get the upstream switch port device.
> + * @pdev: pci device of SGunit
> + *
> + * Device Hierarchy:
> + * Upstream Switch Port (USP) --> Virtual Switch Port (VSP) --> SGunit (GPU endpoint)
> + *
> + * The function traverses the PCI device hierarchy to find the upstream switch port
> + * device.
> + *
> + * Return: pointer to USP &pci_dev, NULL otherwise.
> + */
> +struct pci_dev *xe_pci_get_usp_dev(struct pci_dev *pdev)
> +{
> +	struct pci_dev *vsp;
> +
> +	vsp = pci_upstream_bridge(pdev);
> +	if (!vsp)
> +		return NULL;
> +
> +	return pci_upstream_bridge(vsp);
> +}
> +
>   int xe_register_pci_driver(void)
>   {
>   	return pci_register_driver(&xe_pci_driver);
> diff --git a/drivers/gpu/drm/xe/xe_pci.h b/drivers/gpu/drm/xe/xe_pci.h
> index 11bcc5fe2c5b..3dc3539c3970 100644
> --- a/drivers/gpu/drm/xe/xe_pci.h
> +++ b/drivers/gpu/drm/xe/xe_pci.h
> @@ -11,5 +11,6 @@ struct pci_dev;
>   int xe_register_pci_driver(void);
>   void xe_unregister_pci_driver(void);
>   struct xe_device *xe_pci_to_pf_device(struct pci_dev *pdev);
> +struct pci_dev *xe_pci_get_usp_dev(struct pci_dev *pdev);
>   
>   #endif
> diff --git a/drivers/gpu/drm/xe/xe_ras.c b/drivers/gpu/drm/xe/xe_ras.c
> index 2b1a7cb01b0d..a91c3d924e8c 100644
> --- a/drivers/gpu/drm/xe/xe_ras.c
> +++ b/drivers/gpu/drm/xe/xe_ras.c
> @@ -10,6 +10,7 @@
>   #include "xe_device.h"
>   #include "xe_drm_ras.h"
>   #include "xe_log.h"
> +#include "xe_pci.h"
>   #include "xe_pm.h"
>   #include "xe_printk.h"
>   #include "xe_ras.h"
> @@ -462,22 +463,6 @@ static void get_offline_list(struct xe_device *xe)
>   			      &response, sizeof(response), &response.common, false);
>   }
>   
> -static struct pci_dev *find_usp_dev(struct pci_dev *pdev)
> -{
> -	struct pci_dev *vsp;
> -
> -	/*
> -	 * Device Hierarchy:
> -	 *
> -	 * Upstream Switch Port (USP) --> Virtual Switch Port (VSP) --> SGunit (GPU endpoint)
> -	 */
> -	vsp = pci_upstream_bridge(pdev);
> -	if (!vsp)
> -		return NULL;
> -
> -	return pci_upstream_bridge(vsp);
> -}
> -
>   static void ras_usp_aer_init(struct xe_device *xe)
>   {
>   	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> @@ -485,7 +470,7 @@ static void ras_usp_aer_init(struct xe_device *xe)
>   	u16 aer_cap;
>   	u32 status;
>   
> -	usp = find_usp_dev(pdev);
> +	usp = xe_pci_get_usp_dev(pdev);
>   	if (!usp)
>   		return;
>