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

Tushar Dave
2025-01-17T01:21:35Z

On 1/16/25 11:01, Jason Gunthorpe wrote:
> 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);
>
> ?

Yes :)

- /* 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;
+ /* For mask bits that are 0 copy them from the firmware setting
+ * and apply flags for all the mask bits that are 1.
+ */
+ caps->ctrl = (caps->fw_ctrl & ~mask) | (flags & mask);

I ran some sanity tests and looks good. Can I send V2 now?

-Tushar

>
> Jason