linux-kernel - [PATCH 4.9 19/92] drm/ast: Remove existing framebuffers before loading driver

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Message-Id: <20181129140107.929434946@linuxfoundation.org>
Date:   Thu, 29 Nov 2018 15:11:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Thomas Zimmermann <tzimmermann@...e.de>,
        "Y.C. Chen" <yc_chen@...eedtech.com>,
        Jean Delvare <jdelvare@...e.de>,
        Dave Airlie <airlied@...hat.com>
Subject: [PATCH 4.9 19/92] drm/ast: Remove existing framebuffers before loading driver

4.9-stable 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>
Cc: <stable@...r.kernel.org>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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 const struct pci_device_id pciidl

 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
+	drm_fb_helper_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);
 }