linux-kernel - [PATCH 3.16 210/305] drm/ast: Remove existing framebuffers before loading driver

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Message-ID: <lsq.1549201508.119109687@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Thomas Zimmermann" <tzimmermann@...e.de>,
        "Y.C. Chen" <yc_chen@...eedtech.com>,
        "Dave Airlie" <airlied@...hat.com>,
        "Jean Delvare" <jdelvare@...e.de>
Subject: [PATCH 3.16 210/305] drm/ast: Remove existing framebuffers before
 loading driver

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Zimmermann <tzimmermann@...e.de>

commit 5478ad10e7850ce3d8b7056db05ddfa3c9ddad9a upstream.

If vesafb attaches to the AST device, it configures the framebuffer memory
for uncached access by default. When ast.ko later tries to attach itself to
the device, it wants to use write-combining on the framebuffer memory, but
vesefb's existing configuration for uncached access takes precedence. This
results in reduced performance.

Removing the framebuffer's configuration before loding the AST driver fixes
the problem. Other DRM drivers already contain equivalent code.

Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1112963
Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
Tested-by: Y.C. Chen <yc_chen@...eedtech.com>
Reviewed-by: Jean Delvare <jdelvare@...e.de>
Tested-by: Jean Delvare <jdelvare@...e.de>
Signed-off-by: Dave Airlie <airlied@...hat.com>
[bwh: Backported to 3.16: Use remove_conflicting_framebuffers()]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/ast/ast_drv.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

--- a/drivers/gpu/drm/ast/ast_drv.c
+++ b/drivers/gpu/drm/ast/ast_drv.c
@@ -60,8 +60,29 @@ static DEFINE_PCI_DEVICE_TABLE(pciidlist
 
 MODULE_DEVICE_TABLE(pci, pciidlist);
 
+static void ast_kick_out_firmware_fb(struct pci_dev *pdev)
+{
+	struct apertures_struct *ap;
+	bool primary = false;
+
+	ap = alloc_apertures(1);
+	if (!ap)
+		return;
+
+	ap->ranges[0].base = pci_resource_start(pdev, 0);
+	ap->ranges[0].size = pci_resource_len(pdev, 0);
+
+#ifdef CONFIG_X86
+	primary = pdev->resource[PCI_ROM_RESOURCE].flags & IORESOURCE_ROM_SHADOW;
+#endif
+	remove_conflicting_framebuffers(ap, "astdrmfb", primary);
+	kfree(ap);
+}
+
 static int ast_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
+	ast_kick_out_firmware_fb(pdev);
+
 	return drm_get_pci_dev(pdev, ent, &driver);
 }