Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx> writes:
> On Tue, Dec 10, 2024 at 08:49:40AM +0530, Aneesh Kumar K.V wrote:
>>
>> Hi Dan,
>>
>> Dan Williams <dan.j.williams@xxxxxxxxx> writes:
>> > +int pci_ide_stream_setup(struct pci_dev *pdev, struct pci_ide *ide,
>> > + enum pci_ide_flags flags)
>> > +{
>> > + struct pci_host_bridge *hb = pci_find_host_bridge(pdev->bus);
>> > + struct pci_dev *rp = pcie_find_root_port(pdev);
>> > + int mem = 0, rc;
>> > +
>> > + if (ide->stream_id < 0 || ide->stream_id > U8_MAX) {
>> > + pci_err(pdev, "Setup fail: Invalid stream id: %d\n", ide->stream_id);
>> > + return -ENXIO;
>> > + }
>> > +
>> > + if (test_and_set_bit_lock(ide->stream_id, hb->ide_stream_ids)) {
>> > + pci_err(pdev, "Setup fail: Busy stream id: %d\n",
>> > + ide->stream_id);
>> > + return -EBUSY;
>> > + }
>> > +
>>
>> Considering we are using the hostbridge ide_stream_ids bitmap, why is
>> the stream_id allocation not generic? ie, any reason why a stream id alloc
>> like below will not work?
>
> Should be illustrating in commit log.
>
> "The other design detail for TSM-coordinated IDE establishment is that
> the TSM manages allocation of stream-ids, this is why the stream_id is
> passed in to pci_ide_stream_setup()."
>
> This is true for Intel TDX.
>
IIUC ide->stream_id is going to be set by SVE or TDX backend. But then
we also expect the below.
if (test_and_set_bit_lock(ide->stream_id, hb->ide_stream_ids)) {
pci_err(pdev, "Setup fail: Busy stream id: %d\n",
Hence the confusion why the stream-id cannot be allocated by the generic
TSM module as below
>>
>> static int pcie_ide_sel_streamid_alloc(struct pci_dev *pdev)
>> {
>> int stream_id;
>> struct pci_host_bridge *hb;
>>
>> hb = pci_find_host_bridge(pdev->bus);
>>
>> stream_id = find_first_zero_bit(hb->ide_stream_ids, hb->nr_ide_streams);
>> if (stream_id >= hb->nr_ide_streams)
>> return -EBUSY;
>>
>> return stream_id;
>> }
>
-aneesh
