[PATCH] drm/ast: Remove existing framebuffers before loading driver

[PATCH] drm/ast: Remove existing framebuffers before loading driver

[Thomas Zimmermann]

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@suse.de>
Tested-by: Y.C. Chen <yc_chen@aspeedtech.com>
---
 drivers/gpu/drm/ast/ast_drv.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/ast/ast_drv.c b/drivers/gpu/drm/ast/ast_drv.c
index 69dab82a3771..bf589c53b908 100644
--- 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 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
+	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);
 }
 
-- 
2.19.1

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Re: [PATCH] drm/ast: Remove existing framebuffers before loading driver

[Jean Delvare]

On Thu, 2018-11-15 at 11:42 +0100, Thomas Zimmermann wrote:
> 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@suse.de>
> Tested-by: Y.C. Chen <yc_chen@aspeedtech.com>
> ---
>  drivers/gpu/drm/ast/ast_drv.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/ast/ast_drv.c b/drivers/gpu/drm/ast/ast_drv.c
> index 69dab82a3771..bf589c53b908 100644
> --- 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 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
> +	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);
>  }
>  

Thank you very much Thomas.

Reviewed-by: Jean Delvare <jdelvare@suse.de>
Tested-by: Jean Delvare <jdelvare@suse.de>

-- 
Jean Delvare
SUSE L3 Support
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