NACK/Cmnt: [PATCH 1/1][SRU][F/OEM-5.6/G] UBUNTU: SAUCE: PCI: vmd: Add AHCI to fast interrupt list

[Stefan Bader]

On 08.09.20 10:03, You-Sheng Yang wrote:
> From: Jon Derrick <jonathan.derrick at intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1894778
> 
> Some platforms have an AHCI controller behind VMD. These platforms are
> working correctly except for a case when the AHCI MSI is programmed with
> VMD IRQ vector 0 (0xfee00000). When programmed with any other interrupt
> (0xfeeNN000), the MSI is routed correctly and is handled by VMD. Placing
> the AHCI MSI(s) in the fast-interrupt allow list solves the issue.
> 
> This also requires that VMD allocate more than one MSI/X vector and
> changes the minimum MSI/X vectors allocated to two.
> 
> Signed-off-by: Jon Derrick <jonathan.derrick at intel.com>
> (cherry-picked from https://patchwork.kernel.org/patch/11758345/)
> Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
> ---

This change to generic code still is not even on linux-next and there was no
feedback at all about plans for going upstream. Without that we risk having to
carry forward this change for eternity.

-Stefan

>  drivers/pci/controller/vmd.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index 41f4c1c825e6..7668988ed6b5 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -199,15 +199,13 @@ static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd, struct msi_desc *d
>  	int i, best = 1;
>  	unsigned long flags;
>  
> -	if (vmd->msix_count == 1)
> -		return &vmd->irqs[0];
> -
>  	/*
> -	 * White list for fast-interrupt handlers. All others will share the
> +	 * Allow list for fast-interrupt handlers. All others will share the
>  	 * "slow" interrupt vector.
>  	 */
>  	switch (msi_desc_to_pci_dev(desc)->class) {
>  	case PCI_CLASS_STORAGE_EXPRESS:
> +	case PCI_CLASS_STORAGE_SATA_AHCI:
>  		break;
>  	default:
>  		return &vmd->irqs[0];
> @@ -778,7 +776,7 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  	if (vmd->msix_count < 0)
>  		return -ENODEV;
>  
> -	vmd->msix_count = pci_alloc_irq_vectors(dev, 1, vmd->msix_count,
> +	vmd->msix_count = pci_alloc_irq_vectors(dev, 2, vmd->msix_count,
>  					PCI_IRQ_MSIX);
>  	if (vmd->msix_count < 0)
>  		return vmd->msix_count;
> 


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