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    SubjectRe: [PATCH] ata: ahci: Lookup PCS register offset based on PCI device ID
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    On 8/12/19 6:02 AM, Stephen Douthit wrote:
    > On 8/10/19 3:43 AM, Christoph Hellwig wrote:
    >> On Thu, Aug 08, 2019 at 08:24:31PM +0000, Stephen Douthit wrote:
    >>> Intel moved the PCS register from 0x92 to 0x94 on Denverton for some
    >>> reason, so now we get to check the device ID before poking it on reset.
    >>
    >> And now you just match on the new IDs, which means we'll perpetually
    >> catch up on any new device. Dan, can you reach out inside Intel to
    >> figure out if there is a way to find out the PCS register location
    >> without the PCI ID check?
    >>
    >>
    >>> static int ahci_pci_reset_controller(struct ata_host *host)
    >>> {
    >>> struct pci_dev *pdev = to_pci_dev(host->dev);
    >>> @@ -634,13 +669,14 @@ static int ahci_pci_reset_controller(struct ata_host *host)
    >>>
    >>> if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
    >>> struct ahci_host_priv *hpriv = host->private_data;
    >>> + int pcs = ahci_pcs_offset(host);
    >>> u16 tmp16;
    >>>
    >>> /* configure PCS */
    >>> - pci_read_config_word(pdev, 0x92, &tmp16);
    >>> + pci_read_config_word(pdev, pcs, &tmp16);
    >>> if ((tmp16 & hpriv->port_map) != hpriv->port_map) {
    >>> - tmp16 |= hpriv->port_map;
    >>> - pci_write_config_word(pdev, 0x92, tmp16);
    >>> + tmp16 |= hpriv->port_map & 0xff;
    >>> + pci_write_config_word(pdev, pcs, tmp16);
    >>> }
    >>> }
    >>
    >> And Stephen, while you are at it, can you split this Intel-specific
    >> quirk into a separate helper?
    >
    > I can do that. I'll wait until we hear back from Dan if there's a
    > better scheme than a device ID lookup.

    I'll drop the previous series for now.

    --
    Jens Axboe

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