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, 32 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 56c78e93440f..35a533e4c01d 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -44,6 +44,35 @@ static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
 	return 0;
 }
 
+static int ehci_quirk_amd_SB800(struct ehci_hcd *ehci)
+{
+	struct pci_dev *amd_smbus_dev;
+	u8 rev = 0;
+
+	amd_smbus_dev = pci_get_device(PCI_VENDOR_ID_ATI, 0x4385, NULL);
+	if (!amd_smbus_dev)
+		return 0;
+
+	pci_read_config_byte(amd_smbus_dev, PCI_REVISION_ID, &rev);
+	if (rev < 0x40) {
+		pci_dev_put(amd_smbus_dev);
+		amd_smbus_dev = NULL;
+		return 0;
+	}
+
+	if (!amd_nb_dev)
+		amd_nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, 0x1510, NULL);
+	if (!amd_nb_dev)
+		ehci_err(ehci, "QUIRK: unable to get AMD NB device\n");
+
+	ehci_info(ehci, "QUIRK: Enable AMD SB800 L1 fix\n");
+
+	pci_dev_put(amd_smbus_dev);
+	amd_smbus_dev = NULL;
+
+	return 1;
+}
+
 /* called during probe() after chip reset completes */
 static int ehci_pci_setup(struct usb_hcd *hcd)
 {
@@ -102,6 +131,9 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
 	/* cache this readonly data; minimize chip reads */
 	ehci->hcs_params = ehci_readl(ehci, &ehci->caps->hcs_params);
 
+	if (ehci_quirk_amd_SB800(ehci))
+		ehci->amd_l1_fix = 1;
+
 	retval = ehci_halt(ehci);
 	if (retval)
 		return retval;