Commit:     3d46b2e2faa56d12c6d51bf1071fd11abd009d0b
Parent:     6004bda1cce51273ac9e71a39e680831b9ff4503
Author:     Paul Mundt <[EMAIL PROTECTED]>
AuthorDate: Thu Nov 8 11:14:56 2007 +0900
Committer:  Jeff Garzik <[EMAIL PROTECTED]>
CommitDate: Thu Nov 8 13:08:41 2007 -0500

    libata: Support PIO polling-only hosts.
    By default ata_host_activate() expects a valid IRQ in order to
    successfully register the host. This patch enables a special case
    for registering polling-only hosts that either don't have IRQs
    or have buggy IRQ generation (either in terms of handling or
    sensing), which otherwise work fine.
    Hosts that want to use polling mode can simply set ATA_FLAG_PIO_POLLING
    and pass in an invalid IRQ.
    Signed-off-by: Paul Mundt <[EMAIL PROTECTED]>
    Signed-off-by: Jeff Garzik <[EMAIL PROTECTED]>
 drivers/ata/libata-core.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index ec3ce12..89fd0e9 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -7178,6 +7178,10 @@ int ata_host_register(struct ata_host *host, struct 
scsi_host_template *sht)
  *     request IRQ and register it.  This helper takes necessasry
  *     arguments and performs the three steps in one go.
+ *     An invalid IRQ skips the IRQ registration and expects the host to
+ *     have set polling mode on the port. In this case, @irq_handler
+ *     should be NULL.
+ *
  *     LOCKING:
  *     Inherited from calling layer (may sleep).
@@ -7194,6 +7198,12 @@ int ata_host_activate(struct ata_host *host, int irq,
        if (rc)
                return rc;
+       /* Special case for polling mode */
+       if (!irq) {
+               WARN_ON(irq_handler);
+               return ata_host_register(host, sht);
+       }
        rc = devm_request_irq(host->dev, irq, irq_handler, irq_flags,
                              dev_driver_string(host->dev), host);
        if (rc)
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