linux-kernel - Re: [PATCH] ahci: don't use MSI when PCI is disabled

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Message-ID: <CAPcyv4gSjWZ7OPqp9fwtc9yGV9g5AKkkCLDnU-F71XsHBgYUQA@mail.gmail.com>
Date:	Mon, 23 Nov 2015 09:25:38 -0800
From:	Dan Williams <dan.j.williams@...el.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Tejun Heo <tj@...nel.org>,
	"IDE/ATA development list" <linux-ide@...r.kernel.org>,
	Ricardo Neri <ricardo.neri@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ahci: don't use MSI when PCI is disabled

On Mon, Nov 23, 2015 at 1:47 AM, Arnd Bergmann <arnd@...db.de> wrote:
> The AHCI driver is used for some on-chip devices that do not
> use PCI for probing, and it can be built even when CONFIG_PCI
> is disabled, but that now results in a build failure:
>
> ata/libahci.c: In function 'ahci_host_activate_multi_irqs':
> ata/libahci.c:2475:4: error: invalid use of undefined type 'struct msix_entry'
> ata/libahci.c:2475:21: error: dereferencing pointer to incomplete type 'struct msix_entry'
>
> This adds an #ifdef so we use that code only if actual PCI MSI
> is available.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> Fixes: d684a90d38e2 ("ahci: per-port msix support")
>
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 1b6c7cc415bf..54fe01d8145b 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -1796,7 +1796,8 @@ static void ahci_port_intr(struct ata_port *ap)
>         ahci_handle_port_interrupt(ap, port_mmio, status);
>  }
>
> -static irqreturn_t ahci_multi_irqs_intr_hard(int irq, void *dev_instance)
> +static irqreturn_t __maybe_unused ahci_multi_irqs_intr_hard(int irq,
> +                                                           void *dev_instance)
>  {
>         struct ata_port *ap = dev_instance;
>         void __iomem *port_mmio = ahci_port_base(ap);
> @@ -2454,6 +2455,7 @@ void ahci_set_em_messages(struct ahci_host_priv *hpriv,
>  }
>  EXPORT_SYMBOL_GPL(ahci_set_em_messages);
>
> +#ifdef CONFIG_PCI_MSI
>  static int ahci_host_activate_multi_irqs(struct ata_host *host,
>                                          struct scsi_host_template *sht)
>  {
> @@ -2492,6 +2494,7 @@ static int ahci_host_activate_multi_irqs(struct ata_host *host,
>
>         return ata_host_register(host, sht);
>  }
> +#endif
>
>  /**
>   *     ahci_host_activate - start AHCI host, request IRQs and register it
> @@ -2510,9 +2513,12 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
>         int irq = hpriv->irq;
>         int rc;
>
> +#ifdef CONFIG_PCI_MSI
>         if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX))
>                 rc = ahci_host_activate_multi_irqs(host, sht);
> -       else if (hpriv->flags & AHCI_HFLAG_EDGE_IRQ)
> +       else
> +#endif
> +       if (hpriv->flags & AHCI_HFLAG_EDGE_IRQ)
>                 rc = ata_host_activate(host, irq, ahci_single_edge_irq_intr,
>                                        IRQF_SHARED, sht);
>         else
>

If we had an "static inline ahci_irq_vector(int port)"  helper to
compile out the struct msix_entry de-reference would that be
sufficient?
--
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