ahci: per-port msix support
Some AHCI controllers support per-port MSI-X vectors. At the same time
the Linux AHCI driver needs to support one-off architectures that
implement a single MSI-X vector for all ports. The heuristic for
enabling AHCI ports becomes, in order of preference:
1/ per-port multi-MSI-X
2/ per-port multi-MSI
3/ single MSI
4/ single MSI-X
5/ legacy INTX
This all depends on AHCI implementations with potentially broken MSI-X
requesting less vectors than the number of ports. If this assumption is
violated we will need to start explicitly white-listing AHCI-MSIX
implementations.
Reported-by: Ricardo Neri <ricardo.neri@intel.com>
[ricardo: fix struct msix_entry handling]
Reported-by: kernel test robot <ying.huang@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index cdfbcc5..594fcab 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1306,15 +1306,13 @@
#endif
/*
- * ahci_init_msix() only implements single MSI-X support, not multiple
- * MSI-X per-port interrupts. This is needed for host controllers that only
- * have MSI-X support implemented, but no MSI or intx.
+ * ahci_init_msix() - optionally enable per-port MSI-X otherwise defer
+ * to single msi.
*/
static int ahci_init_msix(struct pci_dev *pdev, unsigned int n_ports,
- struct ahci_host_priv *hpriv)
+ struct ahci_host_priv *hpriv, unsigned long flags)
{
- int rc, nvec;
- struct msix_entry entry = {};
+ int nvec, i, rc;
/* Do not init MSI-X if MSI is disabled for the device */
if (hpriv->flags & AHCI_HFLAG_NO_MSI)
@@ -1324,22 +1322,39 @@
if (nvec < 0)
return nvec;
- if (!nvec) {
+ /*
+ * Proper MSI-X implementations will have a vector per-port.
+ * Barring that, we prefer single-MSI over single-MSIX. If this
+ * check fails (not enough MSI-X vectors for all ports) we will
+ * be called again with the flag clear iff ahci_init_msi()
+ * fails.
+ */
+ if (flags & AHCI_HFLAG_MULTI_MSIX) {
+ if (nvec < n_ports)
+ return -ENODEV;
+ nvec = n_ports;
+ } else if (nvec) {
+ nvec = 1;
+ } else {
+ /*
+ * Emit dev_err() since this was the non-legacy irq
+ * method of last resort.
+ */
rc = -ENODEV;
goto fail;
}
- /*
- * There can be more than one vector (e.g. for error detection or
- * hdd hotplug). Only the first vector (entry.entry = 0) is used.
- */
- rc = pci_enable_msix_exact(pdev, &entry, 1);
+ for (i = 0; i < nvec; i++)
+ hpriv->msix[i].entry = i;
+ rc = pci_enable_msix_exact(pdev, hpriv->msix, nvec);
if (rc < 0)
goto fail;
- hpriv->irq = entry.vector;
+ if (nvec > 1)
+ hpriv->flags |= AHCI_HFLAG_MULTI_MSIX;
+ hpriv->irq = hpriv->msix[0].vector; /* for single msi-x */
- return 1;
+ return nvec;
fail:
dev_err(&pdev->dev,
"failed to enable MSI-X with error %d, # of vectors: %d\n",
@@ -1403,20 +1418,25 @@
{
int nvec;
+ /*
+ * Try to enable per-port MSI-X. If the host is not capable
+ * fall back to single MSI before finally attempting single
+ * MSI-X.
+ */
+ nvec = ahci_init_msix(pdev, n_ports, hpriv, AHCI_HFLAG_MULTI_MSIX);
+ if (nvec >= 0)
+ return nvec;
+
nvec = ahci_init_msi(pdev, n_ports, hpriv);
if (nvec >= 0)
return nvec;
- /*
- * Currently, MSI-X support only implements single IRQ mode and
- * exists for controllers which can't do other types of IRQ. Only
- * set it up if MSI fails.
- */
- nvec = ahci_init_msix(pdev, n_ports, hpriv);
+ /* try single-msix */
+ nvec = ahci_init_msix(pdev, n_ports, hpriv, 0);
if (nvec >= 0)
return nvec;
- /* lagacy intx interrupts */
+ /* legacy intx interrupts */
pci_intx(pdev, 1);
hpriv->irq = pdev->irq;
@@ -1578,7 +1598,10 @@
if (!host)
return -ENOMEM;
host->private_data = hpriv;
-
+ hpriv->msix = devm_kzalloc(&pdev->dev,
+ sizeof(struct msix_entry) * n_ports, GFP_KERNEL);
+ if (!hpriv->msix)
+ return -ENOMEM;
ahci_init_interrupts(pdev, n_ports, hpriv);
if (!(hpriv->cap & HOST_CAP_SSS) || ahci_ignore_sss)