[Intel-xe] [PATCH 1/1] drm/xe: REBAR resize should be best effort

[Lucas De Marchi]

On Mon, Jun 05, 2023 at 12:17:05PM -0400, Michael J. Ruhl wrote:
>The resizing of the PCI BAR is a best effort feature.  If it is
>not available, it should not fail the driver probe.
>
>Rework the resize to not exit on failure.
>

I think this deserves a

Fixes: <commit that regressed this>
>Signed-off-by: Michael J. Ruhl <michael.j.ruhl at intel.com>


with this patch, xe module load works again for me on one of my test
systems, thanks.


Acked-by: Lucas De Marchi <lucas.demarchi at intel.com>

Lucas De Marchi

>---
> drivers/gpu/drm/xe/xe_mmio.c | 28 +++++++++++-----------------
> 1 file changed, 11 insertions(+), 17 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_mmio.c b/drivers/gpu/drm/xe/xe_mmio.c
>index 475b14fe4356..f7a7f996b37f 100644
>--- a/drivers/gpu/drm/xe/xe_mmio.c
>+++ b/drivers/gpu/drm/xe/xe_mmio.c
>@@ -47,7 +47,7 @@ static int xe_set_dma_info(struct xe_device *xe)
> 	return err;
> }
>
>-static int
>+static void
> _resize_bar(struct xe_device *xe, int resno, resource_size_t size)
> {
> 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>@@ -61,18 +61,17 @@ _resize_bar(struct xe_device *xe, int resno, resource_size_t size)
> 	if (ret) {
> 		drm_info(&xe->drm, "Failed to resize BAR%d to %dM (%pe). Consider enabling 'Resizable BAR' support in your BIOS\n",
> 			 resno, 1 << bar_size, ERR_PTR(ret));
>-		return ret;
>+		return;
> 	}
>
> 	drm_info(&xe->drm, "BAR%d resized to %dM\n", resno, 1 << bar_size);
>-	return ret;
> }
>
> /*
>  * if force_vram_bar_size is set, attempt to set to the requested size
>  * else set to maximum possible size
>  */
>-static int xe_resize_vram_bar(struct xe_device *xe)
>+static void xe_resize_vram_bar(struct xe_device *xe)
> {
> 	u64 force_vram_bar_size = xe_force_vram_bar_size;
> 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>@@ -83,14 +82,13 @@ static int xe_resize_vram_bar(struct xe_device *xe)
> 	u32 bar_size_mask;
> 	u32 pci_cmd;
> 	int i;
>-	int ret;
>
> 	/* gather some relevant info */
> 	current_size = pci_resource_len(pdev, GEN12_LMEM_BAR);
> 	bar_size_mask = pci_rebar_get_possible_sizes(pdev, GEN12_LMEM_BAR);
>
> 	if (!bar_size_mask)
>-		return 0;
>+		return;
>
> 	/* set to a specific size? */
> 	if (force_vram_bar_size) {
>@@ -104,22 +102,22 @@ static int xe_resize_vram_bar(struct xe_device *xe)
> 			drm_info(&xe->drm,
> 				 "Requested size: %lluMiB is not supported by rebar sizes: 0x%x. Leaving default: %lluMiB\n",
> 				 (u64)rebar_size >> 20, bar_size_mask, (u64)current_size >> 20);
>-			return 0;
>+			return;
> 		}
>
> 		rebar_size = 1ULL << (__fls(bar_size_bit) + BAR_SIZE_SHIFT);
>
> 		if (rebar_size == current_size)
>-			return 0;
>+			return;
> 	} else {
> 		rebar_size = 1ULL << (__fls(bar_size_mask) + BAR_SIZE_SHIFT);
>
> 		/* only resize if larger than current */
> 		if (rebar_size <= current_size)
>-			return 0;
>+			return;
> 	}
>
>-	drm_info(&xe->drm, "Resizing bar from %lluMiB -> %lluMiB\n",
>+	drm_info(&xe->drm, "Attempting to resize bar from %lluMiB -> %lluMiB\n",
> 		 (u64)current_size >> 20, (u64)rebar_size >> 20);
>
> 	while (root->parent)
>@@ -133,17 +131,16 @@ static int xe_resize_vram_bar(struct xe_device *xe)
>
> 	if (!root_res) {
> 		drm_info(&xe->drm, "Can't resize VRAM BAR - platform support is missing. Consider enabling 'Resizable BAR' support in your BIOS\n");
>-		return -1;
>+		return;
> 	}
>
> 	pci_read_config_dword(pdev, PCI_COMMAND, &pci_cmd);
> 	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd & ~PCI_COMMAND_MEMORY);
>
>-	ret = _resize_bar(xe, GEN12_LMEM_BAR, rebar_size);
>+	_resize_bar(xe, GEN12_LMEM_BAR, rebar_size);
>
> 	pci_assign_unassigned_bus_resources(pdev->bus);
> 	pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
>-	return ret;
> }
>
> static bool xe_pci_resource_valid(struct pci_dev *pdev, int bar)
>@@ -163,16 +160,13 @@ static bool xe_pci_resource_valid(struct pci_dev *pdev, int bar)
> static int xe_determine_lmem_bar_size(struct xe_device *xe)
> {
> 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>-	int err;
>
> 	if (!xe_pci_resource_valid(pdev, GEN12_LMEM_BAR)) {
> 		drm_err(&xe->drm, "pci resource is not valid\n");
> 		return -ENXIO;
> 	}
>
>-	err = xe_resize_vram_bar(xe);
>-	if (err)
>-		return err;
>+	xe_resize_vram_bar(xe);
>
> 	xe->mem.vram.io_start = pci_resource_start(pdev, GEN12_LMEM_BAR);
> 	xe->mem.vram.io_size = pci_resource_len(pdev, GEN12_LMEM_BAR);
>-- 
>2.39.2
>