Hi Swaraj,
On Sat, Dec 13, 2025 at 08:22:34PM +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.
>
> Fix this by using devm_request_region() during the probe function.
> This ensures the region is properly reserved and automatically released
> on driver detach.
>
> v1:
> https://lore.kernel.org/lkml/[email protected]/
> Signed-off-by: Swaraj Gaikwad <[email protected]>
> ---
> v2:
> - Use resource_size(&vga_res) instead of hardcoded 64 * 1024.
> - (Feedback from Kees Cook)
>
> 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,
> resource_size(&vga_res), "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;
Any explanation why devm_request_region() is the right choice here?
As per the line above vga_res.start is iomem, and I had expected to see
devm_request_mem_region() used.
I looked only briefly, so I may be wrong.
Sam
