* Re: [PATCH] fbdev: arkfb: Request legacy VGA I/O region
2025-12-13 15:49 [PATCH] fbdev: arkfb: Request legacy VGA I/O region Swaraj Gaikwad
@ 2025-12-13 14:22 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2025-12-13 14:22 UTC (permalink / raw)
To: Swaraj Gaikwad
Cc: Helge Deller, Andrew Morton, Hans Verkuil, Zi Yan, Frank Li,
Bjorn Andersson, Laurent Pinchart, Qianfeng Rong, Vivek Kasireddy,
Konrad Dybcio, Bartosz Golaszewski, open list:FRAMEBUFFER LAYER,
open list:FRAMEBUFFER LAYER, open list, skhan, david.hunter.linux
On Sat, Dec 13, 2025 at 03:49:32PM +0000, Swaraj Gaikwad wrote:
> The arkfb driver uses the legacy VGA I/O range (0x3c0+) but does not
> request it. This can cause conflicts with other drivers that try to
> reserve these ports.
Eek, nice catch!
>
> Fix this by using devm_request_region() during the probe function.
> This ensures the region is properly reserved and automatically released
> on driver detach.
>
> Signed-off-by: Swaraj Gaikwad <swarajgaikwad1925@gmail.com>
> ---
> Compile-tested only on x86_64.
>
> drivers/video/fbdev/arkfb.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c
> index ec084323115f..24e4c20d1a32 100644
> --- a/drivers/video/fbdev/arkfb.c
> +++ b/drivers/video/fbdev/arkfb.c
> @@ -1018,6 +1018,12 @@ static int ark_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
>
> pcibios_bus_to_resource(dev->bus, &vga_res, &bus_reg);
>
> + if (!devm_request_region(&dev->dev, vga_res.start, 64 * 1024, "arkfb-vga")) {
I was expecting to see vga_res.end as the third argument instead of
repeating the open-coded value.
-Kees
> + dev_err(info->device, "cannot reserve legacy VGA ports\n");
> + rc = -EBUSY;
> + goto err_find_mode;
> + }
> +
> par->state.vgabase = (void __iomem *) (unsigned long) vga_res.start;
>
> /* FIXME get memsize */
>
> base-commit: a859eca0e4cc96f63ff125dbe5388d961558b0e9
> --
> 2.52.0
>
--
Kees Cook
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH] fbdev: arkfb: Request legacy VGA I/O region
@ 2025-12-13 15:49 Swaraj Gaikwad
2025-12-13 14:22 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Swaraj Gaikwad @ 2025-12-13 15:49 UTC (permalink / raw)
To: Helge Deller, Andrew Morton, Hans Verkuil, Zi Yan, Frank Li,
Bjorn Andersson, Laurent Pinchart, Qianfeng Rong, Vivek Kasireddy,
Konrad Dybcio, Bartosz Golaszewski, Kees Cook,
open list:FRAMEBUFFER LAYER, open list:FRAMEBUFFER LAYER,
open list
Cc: skhan, david.hunter.linux, Swaraj Gaikwad
The arkfb driver uses the legacy VGA I/O range (0x3c0+) but does not
request it. This can cause conflicts with other drivers that try to
reserve these ports.
Fix this by using devm_request_region() during the probe function.
This ensures the region is properly reserved and automatically released
on driver detach.
Signed-off-by: Swaraj Gaikwad <swarajgaikwad1925@gmail.com>
---
Compile-tested only on x86_64.
drivers/video/fbdev/arkfb.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c
index ec084323115f..24e4c20d1a32 100644
--- a/drivers/video/fbdev/arkfb.c
+++ b/drivers/video/fbdev/arkfb.c
@@ -1018,6 +1018,12 @@ static int ark_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
pcibios_bus_to_resource(dev->bus, &vga_res, &bus_reg);
+ if (!devm_request_region(&dev->dev, vga_res.start, 64 * 1024, "arkfb-vga")) {
+ dev_err(info->device, "cannot reserve legacy VGA ports\n");
+ rc = -EBUSY;
+ goto err_find_mode;
+ }
+
par->state.vgabase = (void __iomem *) (unsigned long) vga_res.start;
/* FIXME get memsize */
base-commit: a859eca0e4cc96f63ff125dbe5388d961558b0e9
--
2.52.0
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