Re: [PATCH 1/1] PCI: Fix Extend ACS configurability

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Jan 15, 2025 at 07:11:25PM -0800, Tushar Dave wrote:
> @@ -1028,10 +1032,15 @@ static void __pci_config_acs(struct pci_dev *dev,
> struct pci_acs *caps,
> 
>         pci_dbg(dev, "ACS mask  = %#06x\n", mask);
>         pci_dbg(dev, "ACS flags = %#06x\n", flags);
> +       pci_dbg(dev, "ACS control = %#06x\n", caps->ctrl);
> +       pci_dbg(dev, "ACS fw_ctrl = %#06x\n", caps->fw_ctrl);
> 
>         /* If mask is 0 then we copy the bit from the firmware setting. */
> -       caps->ctrl = (caps->ctrl & ~mask) | (caps->fw_ctrl & mask);
> -       caps->ctrl |= flags;
> +       caps->ctrl = (caps->ctrl & mask) | (caps->fw_ctrl & ~mask);
> +
> +       /* Apply the flags */
> +       caps->ctrl &= ~mask;
> +       caps->ctrl |= (flags & mask);

caps->ctrl = (caps->ctrl & mask) & ~mask == 0 - so this is kind of confusing.

What we want is to take the fw_ctl for all bits where mask is 0 and
take flags for all bits where it is 1?

  caps->ctrl = (caps->fw_ctrl & ~mask) | (flags & mask);

?

Jason