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[PATCH RFC 09/77] ahci: Update MSI/MSI-X interrupts enablement code

To: linux-kernel@vger.kernel.org
Subject: [PATCH RFC 09/77] ahci: Update MSI/MSI-X interrupts enablement code
From: Alexander Gordeev <agordeev@redhat.com>
Date: Wed, 2 Oct 2013 12:48:25 +0200
Cc: Alexander Gordeev <agordeev@redhat.com>, Bjorn Helgaas <bhelgaas@google.com>, Ralf Baechle <ralf@linux-mips.org>, Michael Ellerman <michael@ellerman.id.au>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Ingo Molnar <mingo@redhat.com>, Tejun Heo <tj@kernel.org>, Dan Williams <dan.j.williams@intel.com>, Andy King <acking@vmware.com>, Jon Mason <jon.mason@intel.com>, Matt Porter <mporter@kernel.crashing.org>, linux-pci@vger.kernel.org, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux390@de.ibm.com, linux-s390@vger.kernel.org, x86@kernel.org, linux-ide@vger.kernel.org, iss_storagedev@hp.com, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, e1000-devel@lists.sourceforge.net, linux-driver@qlogic.com, Solarflare linux maintainers <linux-net-drivers@solarflare.com>, "VMware, Inc." <pv-drivers@vmware.com>, linux-scsi@vger.kernel.org
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As result of recent re-design of the MSI/MSI-X interrupts enabling
pattern this driver has to be updated to use the new technique to
obtain a optimal number of MSI/MSI-X interrupts required.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
---
 drivers/ata/ahci.c |   56 ++++++++++++++++++++++++++++++++-------------------
 1 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 9d715ae..f1c8838 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1091,26 +1091,40 @@ static inline void ahci_gtf_filter_workaround(struct 
ata_host *host)
 {}
 #endif
 
-int ahci_init_interrupts(struct pci_dev *pdev, struct ahci_host_priv *hpriv)
+int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
+                        struct ahci_host_priv *hpriv)
 {
-       int rc;
-       unsigned int maxvec;
+       int rc, nvec;
 
-       if (!(hpriv->flags & AHCI_HFLAG_NO_MSI)) {
-               rc = pci_enable_msi_block_auto(pdev, &maxvec);
-               if (rc > 0) {
-                       if ((rc == maxvec) || (rc == 1))
-                               return rc;
-                       /*
-                        * Assume that advantage of multipe MSIs is negated,
-                        * so fallback to single MSI mode to save resources
-                        */
-                       pci_disable_msi(pdev);
-                       if (!pci_enable_msi(pdev))
-                               return 1;
-               }
-       }
+       if (hpriv->flags & AHCI_HFLAG_NO_MSI)
+               goto intx;
+
+       rc = pci_get_msi_cap(pdev);
+       if (rc < 0)
+               goto intx;
+
+       /*
+        * If number of MSIs is less than number of ports then Sharing Last
+        * Message mode could be enforced. In this case assume that advantage
+        * of multipe MSIs is negated and use single MSI mode instead.
+        */
+       if (rc < n_ports)
+               goto single_msi;
+
+       nvec = rc;
+       rc = pci_enable_msi_block(pdev, nvec);
+       if (rc)
+               goto intx;
 
+       return nvec;
+
+single_msi:
+       rc = pci_enable_msi(pdev);
+       if (rc)
+               goto intx;
+       return 1;
+
+intx:
        pci_intx(pdev, 1);
        return 0;
 }
@@ -1277,10 +1291,6 @@ static int ahci_init_one(struct pci_dev *pdev, const 
struct pci_device_id *ent)
 
        hpriv->mmio = pcim_iomap_table(pdev)[ahci_pci_bar];
 
-       n_msis = ahci_init_interrupts(pdev, hpriv);
-       if (n_msis > 1)
-               hpriv->flags |= AHCI_HFLAG_MULTI_MSI;
-
        /* save initial config */
        ahci_pci_save_initial_config(pdev, hpriv);
 
@@ -1335,6 +1345,10 @@ static int ahci_init_one(struct pci_dev *pdev, const 
struct pci_device_id *ent)
         */
        n_ports = max(ahci_nr_ports(hpriv->cap), fls(hpriv->port_map));
 
+       n_msis = ahci_init_interrupts(pdev, n_ports, hpriv);
+       if (n_msis > 1)
+               hpriv->flags |= AHCI_HFLAG_MULTI_MSI;
+
        host = ata_host_alloc_pinfo(&pdev->dev, ppi, n_ports);
        if (!host)
                return -ENOMEM;
-- 
1.7.7.6


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