USB: ohci: quirk AMD prefetch for USB 1.1 ISO transfer

The following patch in the driver is required to avoid USB 1.1 device
failures that may occur due to requests from USB OHCI controllers may
be overwritten if the latency for any pending request by the USB
controller is very long (in the range of milliseconds).
Signed-off-by: Libin Yang <libin.yang@amd.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/ohci-hcd.c

@@ -87,6 +87,7 @@ static int ohci_restart (struct ohci_hcd *ohci);
 #ifdef CONFIG_PCI
 static void quirk_amd_pll(int state);
 static void amd_iso_dev_put(void);
+static void sb800_prefetch(struct ohci_hcd *ohci, int on);
 #else
 static inline void quirk_amd_pll(int state)
 {
@@ -96,6 +97,10 @@ static inline void amd_iso_dev_put(void)
 {
 	return;
 }
+static inline void sb800_prefetch(struct ohci_hcd *ohci, int on)
+{
+	return;
+}
 #endif
 
 

drivers/usb/host/ohci-pci.c

@@ -177,6 +177,13 @@ static int ohci_quirk_amd700(struct usb_hcd *hcd)
 		return 0;
 
 	pci_read_config_byte(amd_smbus_dev, PCI_REVISION_ID, &rev);
+
+	/* SB800 needs pre-fetch fix */
+	if ((rev >= 0x40) && (rev <= 0x4f)) {
+		ohci->flags |= OHCI_QUIRK_AMD_PREFETCH;
+		ohci_dbg(ohci, "enabled AMD prefetch quirk\n");
+	}
+
 	if ((rev > 0x3b) || (rev < 0x30)) {
 		pci_dev_put(amd_smbus_dev);
 		amd_smbus_dev = NULL;
@@ -262,6 +269,19 @@ static void amd_iso_dev_put(void)
 
 }
 
+static void sb800_prefetch(struct ohci_hcd *ohci, int on)
+{
+	struct pci_dev *pdev;
+	u16 misc;
+
+	pdev = to_pci_dev(ohci_to_hcd(ohci)->self.controller);
+	pci_read_config_word(pdev, 0x50, &misc);
+	if (on == 0)
+		pci_write_config_word(pdev, 0x50, misc & 0xfcff);
+	else
+		pci_write_config_word(pdev, 0x50, misc | 0x0300);
+}
+
 /* List of quirks for OHCI */
 static const struct pci_device_id ohci_pci_quirks[] = {
 	{

drivers/usb/host/ohci-q.c

@@ -49,9 +49,12 @@ __acquires(ohci->lock)
 	switch (usb_pipetype (urb->pipe)) {
 	case PIPE_ISOCHRONOUS:
 		ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs--;
-		if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0
-				&& quirk_amdiso(ohci))
+		if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0) {
+			if (quirk_amdiso(ohci))
 				quirk_amd_pll(1);
+			if (quirk_amdprefetch(ohci))
+				sb800_prefetch(ohci, 0);
+		}
 		break;
 	case PIPE_INTERRUPT:
 		ohci_to_hcd(ohci)->self.bandwidth_int_reqs--;
@@ -680,9 +683,12 @@ static void td_submit_urb (
 				data + urb->iso_frame_desc [cnt].offset,
 				urb->iso_frame_desc [cnt].length, urb, cnt);
 		}
-		if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0
-				&& quirk_amdiso(ohci))
+		if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0) {
+			if (quirk_amdiso(ohci))
 				quirk_amd_pll(0);
+			if (quirk_amdprefetch(ohci))
+				sb800_prefetch(ohci, 1);
+		}
 		periodic = ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs++ == 0
 			&& ohci_to_hcd(ohci)->self.bandwidth_int_reqs == 0;
 		break;

drivers/usb/host/ohci.h

@@ -402,6 +402,7 @@ struct ohci_hcd {
 #define	OHCI_QUIRK_FRAME_NO	0x80			/* no big endian frame_no shift */
 #define	OHCI_QUIRK_HUB_POWER	0x100			/* distrust firmware power/oc setup */
 #define	OHCI_QUIRK_AMD_ISO	0x200			/* ISO transfers*/
+#define	OHCI_QUIRK_AMD_PREFETCH	0x400			/* pre-fetch for ISO transfer */
 	// there are also chip quirks/bugs in init logic
 
 	struct work_struct	nec_work;	/* Worker for NEC quirk */
@@ -433,6 +434,10 @@ static inline int quirk_amdiso(struct ohci_hcd *ohci)
 {
 	return ohci->flags & OHCI_QUIRK_AMD_ISO;
 }
+static inline int quirk_amdprefetch(struct ohci_hcd *ohci)
+{
+	return ohci->flags & OHCI_QUIRK_AMD_PREFETCH;
+}
 #else
 static inline int quirk_nec(struct ohci_hcd *ohci)
 {
@@ -446,6 +451,10 @@ static inline int quirk_amdiso(struct ohci_hcd *ohci)
 {
 	return 0;
 }
+static inline int quirk_amdprefetch(struct ohci_hcd *ohci)
+{
+	return 0;
+}
 #endif
 
 /* convert between an hcd pointer and the corresponding ohci_hcd */