[PATCH 0/3] PCI: remove redundant resource assignments done after BAR resize

[PATCH 0/3] PCI: remove redundant resource assignments done after BAR resize

[Ilpo Järvinen]

The BAR resize rework removed the resource assignment call that
followed the BAR resize in amdgpu. The xe and i915 drivers and the
PCI sysfs resize interface still make the same call.
 
The current BAR resize code should properly assign all resources and
handle fallback gracefully so a driver-side call to assign resource
right after BAR resize is just duplicate work (no-op). If that isn't
the case somewhere, the fix belongs either the BAR resize code or the
code that left the resource unassigned (e.g. a hotplug race or whatever
left an resource unassigned prior to resize).

If drm wants to take their patches out of these, it's fine with me
(either drm+pci or through pci tree only works for me).


Ilpo Järvinen (3):
  PCI/sysfs: Remove resource assignment after BAR resize
  drm/xe: Remove driver side resource assignment after BAR resize
  drm/i915: Remove driver side resource assignment after BAR resize

 drivers/gpu/drm/i915/gt/intel_region_lmem.c | 1 -
 drivers/gpu/drm/xe/xe_pci_rebar.c           | 2 --
 drivers/pci/pci-sysfs.c                     | 3 ---
 3 files changed, 6 deletions(-)


base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.47.3

[PATCH 1/3] PCI/sysfs: Remove resource assignment after BAR resize

[Ilpo Järvinen]

pci_resize_resource() assigns the resized BAR and the other BARs it
released, or restores the original configuration on failure. Calling
pci_assign_unassigned_bus_resources() after it is redundant. If that
call manages to assign more resources in some scenario, the problem
should be fixed inside pci_resize_resource() instead.

Remove the pci_assign_unassigned_bus_resources() call from
__resource_resize_store().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/pci/pci-sysfs.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 6669e9ad5bd3..bccd0bd5091b 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1731,7 +1731,6 @@ static ssize_t __resource_resize_store(struct device *dev, int n,
 				       const char *buf, size_t count)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
-	struct pci_bus *bus = pdev->bus;
 	unsigned long size;
 	int ret;
 	u16 cmd;
@@ -1768,8 +1767,6 @@ static ssize_t __resource_resize_store(struct device *dev, int n,
 		pci_warn(pdev, "Failed to resize BAR %d: %pe\n",
 			 n, ERR_PTR(ret));
 
-	pci_assign_unassigned_bus_resources(bus);
-
 	if (sysfs_create_groups(&pdev->dev.kobj, pci_dev_resource_attr_groups))
 		pci_warn(pdev, "Failed to recreate resource groups after BAR resizing\n");
 
-- 
2.47.3

[PATCH 2/3] drm/xe: Remove driver side resource assignment after BAR resize

[Ilpo Järvinen]

pci_resize_resource() assigns the resized BAR and the other BARs it
released, or restores the original configuration on failure. Calling
pci_assign_unassigned_bus_resources() after it is redundant. If that
call manages to assign more resources in some scenario, the problem
should be fixed inside pci_resize_resource() instead.

Remove the pci_assign_unassigned_bus_resources() call from
xe_pci_rebar_resize().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/gpu/drm/xe/xe_pci_rebar.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_pci_rebar.c b/drivers/gpu/drm/xe/xe_pci_rebar.c
index 7e2c7079b6ff..f47b3c039abd 100644
--- a/drivers/gpu/drm/xe/xe_pci_rebar.c
+++ b/drivers/gpu/drm/xe/xe_pci_rebar.c
@@ -100,7 +100,5 @@ void xe_pci_rebar_resize(struct xe_device *xe)
 	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd & ~PCI_COMMAND_MEMORY);
 
 	resize_bar(xe, LMEM_BAR, rebar_size);
-
-	pci_assign_unassigned_bus_resources(pdev->bus);
 	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
 }
-- 
2.47.3

[PATCH 3/3] drm/i915: Remove driver side resource assignment after BAR resize

[Ilpo Järvinen]

pci_resize_resource() assigns the resized BAR and the other BARs it
released, or restores the original configuration on failure. Calling
pci_assign_unassigned_bus_resources() after it is redundant. If that
call manages to assign more resources in some scenario, the problem
should be fixed inside pci_resize_resource() instead.

Remove the pci_assign_unassigned_bus_resources() call from
i915_resize_lmem_bar().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/gpu/drm/i915/gt/intel_region_lmem.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
index b8a39567a334..d6f5e340657c 100644
--- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
@@ -104,7 +104,6 @@ static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t
 
 		_resize_bar(i915, GEN12_LMEM_BAR, rebar_size);
 
-		pci_assign_unassigned_bus_resources(pdev->bus);
 		pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
 		intel_uncore_forcewake_put(&i915->uncore, FORCEWAKE_ALL);
 	}
-- 
2.47.3

Re: [PATCH 3/3] drm/i915: Remove driver side resource assignment after BAR resize

[Joonas Lahtinen]

Quoting Ilpo Järvinen (2026-11-09 15:10:10)
> pci_resize_resource() assigns the resized BAR and the other BARs it
> released, or restores the original configuration on failure. Calling
> pci_assign_unassigned_bus_resources() after it is redundant. If that
> call manages to assign more resources in some scenario, the problem
> should be fixed inside pci_resize_resource() instead.
> 
> Remove the pci_assign_unassigned_bus_resources() call from
> i915_resize_lmem_bar().
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Feel free to apply on pci tree where the refactoring also landed.

Regards, Joonas

Re: [PATCH 2/3] drm/xe: Remove driver side resource assignment after BAR resize

[Rodrigo Vivi]

On Mon, Nov 09, 2026 at 03:10:09PM +0200, Ilpo Järvinen wrote:
> pci_resize_resource() assigns the resized BAR and the other BARs it
> released, or restores the original configuration on failure. Calling
> pci_assign_unassigned_bus_resources() after it is redundant. If that
> call manages to assign more resources in some scenario, the problem
> should be fixed inside pci_resize_resource() instead.
> 
> Remove the pci_assign_unassigned_bus_resources() call from
> xe_pci_rebar_resize().
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

feel free to take it through your trees

> ---
>  drivers/gpu/drm/xe/xe_pci_rebar.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pci_rebar.c b/drivers/gpu/drm/xe/xe_pci_rebar.c
> index 7e2c7079b6ff..f47b3c039abd 100644
> --- a/drivers/gpu/drm/xe/xe_pci_rebar.c
> +++ b/drivers/gpu/drm/xe/xe_pci_rebar.c
> @@ -100,7 +100,5 @@ void xe_pci_rebar_resize(struct xe_device *xe)
>  	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd & ~PCI_COMMAND_MEMORY);
>  
>  	resize_bar(xe, LMEM_BAR, rebar_size);
> -
> -	pci_assign_unassigned_bus_resources(pdev->bus);
>  	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
>  }
> -- 
> 2.47.3
>