USB: EHCI: ASPM quirk of ISOC on AMD SB800

When ASPM PM Feature is enabled on UMI link, devices that use ISOC stream of
data transfer may be exposed to longer latency causing less than optimal per-
formance of the device. The longer latencies are normal and are due to link
wake time coming out of low power state which happens frequently to save
power when the link is not active.
The following code will make exception for certain features of ASPM to be by
passed and keep the logic normal state only when the ISOC device is connected
and active. This change will allow the device to run at optimal performance
yet minimize the impact on overall power savings.

Signed-off-by: Alex He <alex.he@amd.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index abe8336ebffa..6778fbcf2416 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -114,6 +114,9 @@ MODULE_PARM_DESC(hird, "host initiated resume duration, +1 for each 75us\n");
 
 #define INTR_MASK (STS_IAA | STS_FATAL | STS_PCD | STS_ERR | STS_INT)
 
+/* for ASPM quirk of ISOC on AMD SB800 */
+static struct pci_dev *amd_nb_dev;
+
 /*-------------------------------------------------------------------------*/
 
 #include "ehci.h"
@@ -529,6 +532,11 @@ static void ehci_stop (struct usb_hcd *hcd)
         spin_unlock_irq (&ehci->lock);
         ehci_mem_cleanup (ehci);
 
+        if (amd_nb_dev) {
+                pci_dev_put(amd_nb_dev);
+                amd_nb_dev = NULL;
+        }
+
 #ifdef  EHCI_STATS
         ehci_dbg (ehci, "irq normal %ld err %ld reclaim %ld (lost %ld)\n",
                 ehci->stats.normal, ehci->stats.error, ehci->stats.reclaim,