linux-kernel - Re: [PATCH] libata/ahci: Fix PCS quirk application

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Message-ID: <e4544252-d2d7-e464-94d6-4df7cda0e248@silicom-usa.com>
Date:   Tue, 15 Oct 2019 21:02:19 +0000
From:   Stephen Douthit <stephend@...icom-usa.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>
CC:     Andreas Friedrich <afrie@....net>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] libata/ahci: Fix PCS quirk application

On 10/15/19 3:54 PM, Dan Williams wrote:
> Commit c312ef176399 "libata/ahci: Drop PCS quirk for Denverton and
> beyond" got the polarity wrong on the check for which board-ids should
> have the quirk applied. The board type board_ahci_pcs7 is defined at the
> end of the list such that "pcs7" boards can be special cased in the
> future if they need the quirk. All prior Intel board ids "<
> board_ahci_pcs7" should proceed with applying the quirk.
> 
> Reported-by: Andreas Friedrich <afrie@....net>
> Reported-by: Stephen Douthit <stephend@...icom-usa.com>
> Fixes: c312ef176399 ("libata/ahci: Drop PCS quirk for Denverton and beyond")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>   drivers/ata/ahci.c |    4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index dd92faf197d5..05c2b32dcc4d 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -1600,7 +1600,9 @@ static void ahci_intel_pcs_quirk(struct pci_dev *pdev, struct ahci_host_priv *hp
>   	 */
>   	if (!id || id->vendor != PCI_VENDOR_ID_INTEL)
>   		return;

Unless I'm missing something this will short-circuit if there are any
older Intel controllers not explicitly listed with a PCI_VDEVICE entry
in ahci_pci_tbl.  Those will match on:

	/* Generic, PCI class code for AHCI */
	{ PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
	  PCI_CLASS_STORAGE_SATA_AHCI, 0xffffff, board_ahci },

and id->vendor will be PCI_ANY_ID so we bail before applying the quirk.
because....

static inline const struct pci_device_id *
pci_match_one_device(const struct pci_device_id *id, const struct pci_dev *dev)
{
	if ((id->vendor == PCI_ANY_ID || id->vendor == dev->vendor) &&
	    (id->device == PCI_ANY_ID || id->device == dev->device) &&
	    (id->subvendor == PCI_ANY_ID || id->subvendor == dev->subsystem_vendor) &&
	    (id->subdevice == PCI_ANY_ID || id->subdevice == dev->subsystem_device) &&
	    !((id->class ^ dev->class) & id->class_mask))
		return id;
	return NULL;
}

const struct pci_device_id *pci_match_id(const struct pci_device_id *ids,
					 struct pci_dev *dev)
{
	if (ids) {
		while (ids->vendor || ids->subvendor || ids->class_mask) {
			if (pci_match_one_device(ids, dev))
				return ids;
			ids++;
		}
	}
	return NULL;
}

So we should check pdev->vendor instead.

-Steve

> -	if (((enum board_ids) id->driver_data) < board_ahci_pcs7)
> +
> +	/* Skip applying the quirk on Denverton and beyond */
> +	if (((enum board_ids) id->driver_data) >= board_ahci_pcs7)
>   		return;
>   
>   	/*
>