does dtb not support pci acs enable?

[steven <steven_ygui@163.com>]

Hello,

I am a new person in PCI, I am trying to do something for iommu group on arm64 platform, I found if I boot the linux (5.10 kernel) kernel using UEFI + ACPI, it will work correctly. But if I boot it using UEFI + DTB, the iommu group not work, only one group present.

I read the code, found that pci_acs_enable is set to 1 during acpi_init, but I can not find any code for dtb booting, so it will return "disable_acs_redir " during call pci_enable_acs. 
static void pci_enable_acs(struct pci_dev *dev)
{
    if (!pci_acs_enable)
        goto disable_acs_redir;

    if (!pci_dev_specific_enable_acs(dev))
        goto disable_acs_redir;

    pci_std_enable_acs(dev);




SO, is it not support in dtb?