linux-kernel - [PATCH v8 08/10] vgaarb: Log bridge control messages when adding devices

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Date:   Wed,  5 Jan 2022 18:06:56 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>
Cc:     Xuefeng Li <lixuefeng@...ngson.cn>,
        Huacai Chen <chenhuacai@...il.com>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        linux-pci@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v8 08/10] vgaarb: Log bridge control messages when adding devices

From: Huacai Chen <chenhuacai@...ngson.cn>

Previously vga_arb_device_init() iterated through all VGA devices and
indicated whether legacy VGA routing to each could be controlled by an
upstream bridge.

But we determine that information in vga_arbiter_add_pci_device(), which we
call for every device, so we can log it there without iterating through the
VGA devices again.

Note that we call vga_arbiter_check_bridge_sharing() before adding the
device to vga_list, so we have to handle the very first device separately.

Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/gpu/vga/vgaarb.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 455cf048fae8..b7e6c1228fff 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -719,8 +719,10 @@ static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
 
 	vgadev->bridge_has_one_vga = true;
 
-	if (list_empty(&vga_list))
+	if (list_empty(&vga_list)) {
+		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
 		return;
+	}
 
 	/* okay iterate the new devices bridge hierarachy */
 	new_bus = vgadev->pdev->bus;
@@ -759,6 +761,11 @@ static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
 		}
 		new_bus = new_bus->parent;
 	}
+
+	if (vgadev->bridge_has_one_vga)
+		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
+	else
+		vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
 }
 
 /*
@@ -1557,7 +1564,6 @@ static int __init vga_arb_device_init(void)
 {
 	int rc;
 	struct pci_dev *pdev;
-	struct vga_device *vgadev;
 
 	rc = misc_register(&vga_arb_device);
 	if (rc < 0)
@@ -1573,15 +1579,6 @@ static int __init vga_arb_device_init(void)
 			       PCI_ANY_ID, pdev)) != NULL)
 		vga_arbiter_add_pci_device(pdev);
 
-	list_for_each_entry(vgadev, &vga_list, list) {
-		struct device *dev = &vgadev->pdev->dev;
-
-		if (vgadev->bridge_has_one_vga)
-			vgaarb_info(dev, "bridge control possible\n");
-		else
-			vgaarb_info(dev, "no bridge control possible\n");
-	}
-
 	pr_info("loaded\n");
 	return rc;
 }
-- 
2.25.1