[PATCH] ehci: disable LPM and PPCD for nVidia MCP89 chips

["Brian J. Tarricone" <brian@tarricone.org>]

From: Brian Tarricone <brian@tarricone.org>

Tested on MacBookAir3,1.  Without this, we get EPROTO errors when
fetching device config descriptors.

Signed-off-by: Brian Tarricone <brian@tarricone.org>
Reported-by: Benoit Gschwind <gschwind@gnu-log.net>
Tested-by: Edgar Hucek <gimli@dark-green.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
---
 drivers/usb/host/ehci-pci.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index a1e8d27..aa79f98 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -148,6 +148,18 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
 			if (pdev->revision < 0xa4)
 				ehci->no_selective_suspend = 1;
 			break;
+
+		/* MCP89 chips on the MacBookAir3,1 give EPROTO when
+		 * fetching device descriptors unless LPM is disabled.
+		 * There are also intermittent problems enumerating
+		 * devices with PPCD enabled.
+		 */
+		case 0x0d9d:
+			ehci_info(ehci, "disable lpm/ppcd for nvidia mcp89");
+			ehci->has_lpm = 0;
+			ehci->has_ppcd = 0;
+			ehci->command &= ~(CMD_PPCEE);
+			break;
 		}
 		break;
 	case PCI_VENDOR_ID_VIA:
-- 
1.7.2.2