libata: Add a per-host flag to opt-in into parallel port probes

This patch adds a per host flag that allows drivers to opt in into
having its busses scanned in parallel.

Drivers that do not set this flag get their ports scanned in
the "original" sequence.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 13 insertions, 0 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 7f701cbe14ab..96039671e3b9 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -2660,6 +2660,9 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         host->iomap = pcim_iomap_table(pdev);
         host->private_data = hpriv;
 
+        if (!(hpriv->cap & HOST_CAP_SSS))
+                host->flags |= ATA_HOST_PARALLEL_SCAN;
+
         if (pi.flags & ATA_FLAG_EM)
                 ahci_reset_em(host);
 
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index c507a9ac78f4..f810078fafcc 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5920,6 +5920,15 @@ static void async_port_probe(void *data, async_cookie_t cookie)
 {
         int rc;
         struct ata_port *ap = data;
+
+        /*
+         * If we're not allowed to scan this host in parallel,
+         * we need to wait until all previous scans have completed
+         * before going further.
+         */
+        if (!(ap->host->flags & ATA_HOST_PARALLEL_SCAN))
+                async_synchronize_cookie(cookie);
+
         /* probe */
         if (ap->ops->error_handler) {
                 struct ata_eh_info *ehi = &ap->link.eh_info;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 4f7c8fb4d3fe..b6b8a7f3ec66 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -239,6 +239,7 @@ enum {
         /* host set flags */
         ATA_HOST_SIMPLEX        = (1 << 0),     /* Host is simplex, one DMA channel per host only */
         ATA_HOST_STARTED        = (1 << 1),     /* Host started */
+        ATA_HOST_PARALLEL_SCAN  = (1 << 2),     /* Ports on this host can be scanned in parallel */
 
         /* bits 24:31 of host->flags are reserved for LLD specific flags */