Re: [linux-usb-devel] Re: ATI RS480-based motherboard: stuck while booting with kernel >= 2.6.15 rc1

[David Brownell <david-b@pacbell.net>]

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> OK, so it sounds like quirk_usb_disable_ehci() caused your machine to hang
> with the old BIOS.  That's fairly bad behaviour from the kernel, even
> though the BIOS presumably had some problems.

I think what happened is the "always run quirks" code got turned into
the default too early, before the EHCI "quirk" version of the handoff
code got checked against what most systems have been using for the past
several years.

I noticed at least one suspicous thing:  it enables an SMI IRQ.
Even in cases when the boot firmware says it's not using EHCI ...
easy to imagine that causing hangage.


Maybe this time it'd help to tell your BIOS "yes, DO use USB".
Or, the attached patch might help.  Please try both experiments.

- Dave



[-- Attachment #2: ehci-handoff.patch --]
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This moves the previously widely-used ehci-pci.c BIOS handoff
code into the pci-quirks.c file, replacing the less widely used
"early handoff" version that seems to cause problems lately.

One notable change:  the "early handoff" version always enabled
an SMI IRQ ... and did so even if the pre-Linux code said it was
not using EHCI (and not expecting EHCI SMIs).  Looks like a goof
in a workaround for some unknown BIOS version.

This merged version only forcibly enables those IRQs when pre-Linux
code says it's using EHCI.  And now it always forces them off "just
in case".

EXPERIMENTAL


Index: g26/drivers/usb/host/ehci-pci.c
===================================================================
--- g26.orig/drivers/usb/host/ehci-pci.c	2006-01-15 12:59:13.000000000 -0800
+++ g26/drivers/usb/host/ehci-pci.c	2006-01-22 09:17:54.000000000 -0800
@@ -24,40 +24,6 @@
 
 /*-------------------------------------------------------------------------*/
 
-/* EHCI 0.96 (and later) section 5.1 says how to kick BIOS/SMM/...
- * off the controller (maybe it can boot from highspeed USB disks).
- */
-static int bios_handoff(struct ehci_hcd *ehci, int where, u32 cap)
-{
-	struct pci_dev *pdev = to_pci_dev(ehci_to_hcd(ehci)->self.controller);
-
-	/* always say Linux will own the hardware */
-	pci_write_config_byte(pdev, where + 3, 1);
-
-	/* maybe wait a while for BIOS to respond */
-	if (cap & (1 << 16)) {
-		int msec = 5000;
-
-		do {
-			msleep(10);
-			msec -= 10;
-			pci_read_config_dword(pdev, where, &cap);
-		} while ((cap & (1 << 16)) && msec);
-		if (cap & (1 << 16)) {
-			ehci_err(ehci, "BIOS handoff failed (%d, %08x)\n",
-				where, cap);
-			// some BIOS versions seem buggy...
-			// return 1;
-			ehci_warn(ehci, "continuing after BIOS bug...\n");
-			/* disable all SMIs, and clear "BIOS owns" flag */
-			pci_write_config_dword(pdev, where + 4, 0);
-			pci_write_config_byte(pdev, where + 2, 0);
-		} else
-			ehci_dbg(ehci, "BIOS handoff succeeded\n");
-	}
-	return 0;
-}
-
 /* called after powerup, by probe or system-pm "wakeup" */
 static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
 {
@@ -84,32 +50,9 @@ static int ehci_pci_reinit(struct ehci_h
 		}
 	}
 
-	temp = HCC_EXT_CAPS(readl(&ehci->caps->hcc_params));
-
-	/* EHCI 0.96 and later may have "extended capabilities" */
-	while (temp && count--) {
-		u32		cap;
-
-		pci_read_config_dword(pdev, temp, &cap);
-		ehci_dbg(ehci, "capability %04x at %02x\n", cap, temp);
-		switch (cap & 0xff) {
-		case 1:			/* BIOS/SMM/... handoff */
-			if (bios_handoff(ehci, temp, cap) != 0)
-				return -EOPNOTSUPP;
-			break;
-		case 0:			/* illegal reserved capability */
-			ehci_dbg(ehci, "illegal capability!\n");
-			cap = 0;
-			/* FALLTHROUGH */
-		default:		/* unknown */
-			break;
-		}
-		temp = (cap >> 8) & 0xff;
-	}
-	if (!count) {
-		ehci_err(ehci, "bogus capabilities ... PCI problems!\n");
-		return -EIO;
-	}
+	/* we expect static quirk code to handle the "extended capabilities"
+	 * (currently just BIOS handoff) allowed starting with EHCI 0.96
+	 */
 
 	/* PCI Memory-Write-Invalidate cycle support is optional (uncommon) */
 	retval = pci_set_mwi(pdev);
Index: g26/drivers/usb/host/pci-quirks.c
===================================================================
--- g26.orig/drivers/usb/host/pci-quirks.c	2006-01-05 17:35:38.000000000 -0800
+++ g26/drivers/usb/host/pci-quirks.c	2006-01-22 11:20:52.000000000 -0800
@@ -190,7 +190,7 @@ static void __devinit quirk_usb_handoff_
 			msleep(10);
 		}
 		if (wait_time <= 0)
-			printk(KERN_WARNING "%s %s: early BIOS handoff "
+			printk(KERN_WARNING "%s %s: BIOS handoff "
 					"failed (BIOS bug ?)\n",
 					pdev->dev.bus_id, "OHCI");
 
@@ -212,8 +212,9 @@ static void __devinit quirk_usb_disable_
 {
 	int wait_time, delta;
 	void __iomem *base, *op_reg_base;
-	u32 hcc_params, val, temp;
-	u8 cap_length;
+	u32	hcc_params, val;
+	u8	offset, cap_length;
+	int	count = 256/4;
 
 	if (!mmio_resource_enabled(pdev, 0))
 		return;
@@ -224,51 +225,80 @@ static void __devinit quirk_usb_disable_
 
 	cap_length = readb(base);
 	op_reg_base = base + cap_length;
+
+	/* EHCI 0.96 and later may have "extended capabilities"
+	 * spec section 5.1 explains the bios handoff, e.g. for
+	 * booting from USB disk or using a usb keyboard
+	 */
 	hcc_params = readl(base + EHCI_HCC_PARAMS);
-	hcc_params = (hcc_params >> 8) & 0xff;
-	if (hcc_params) {
-		pci_read_config_dword(pdev,
-					hcc_params + EHCI_USBLEGSUP,
-					&val);
-		if (((val & 0xff) == 1) && (val & EHCI_USBLEGSUP_BIOS)) {
-			/*
-			 * Ok, BIOS is in smm mode, try to hand off...
-			 */
-			pci_read_config_dword(pdev,
-						hcc_params + EHCI_USBLEGCTLSTS,
-						&temp);
-			pci_write_config_dword(pdev,
-						hcc_params + EHCI_USBLEGCTLSTS,
-						temp | EHCI_USBLEGCTLSTS_SOOE);
-			val |= EHCI_USBLEGSUP_OS;
-			pci_write_config_dword(pdev,
-						hcc_params + EHCI_USBLEGSUP,
-						val);
+	offset = (hcc_params >> 8) & 0xff;
+	while (offset && count--) {
+		u32		cap;
+		int		msec;
+
+		pci_read_config_dword(pdev, offset, &cap);
+		switch (cap & 0xff) {
+		case 1:			/* BIOS/SMM/... handoff support */
+			if ((cap & EHCI_USBLEGSUP_BIOS)) {
+				pr_debug("%s %s: BIOS handoff\n",
+						pdev->dev.bus_id, "EHCI");
 
-			wait_time = 500;
-			do {
-				msleep(10);
-				wait_time -= 10;
+				/* BIOS workaround (?): be sure the
+				 * pre-Linux code receives the SMI
+				 */
 				pci_read_config_dword(pdev,
-						hcc_params + EHCI_USBLEGSUP,
+						offset + EHCI_USBLEGCTLSTS,
 						&val);
-			} while (wait_time && (val & EHCI_USBLEGSUP_BIOS));
-			if (!wait_time) {
-				/*
-				 * well, possibly buggy BIOS...
+				pci_write_config_dword(pdev,
+						offset + EHCI_USBLEGCTLSTS,
+						val | EHCI_USBLEGCTLSTS_SOOE);
+			}
+
+			/* always say Linux will own the hardware
+			 * by setting EHCI_USBLEGSUP_OS.
+			 */
+			pci_write_config_byte(pdev, offset + 3, 1);
+
+			/* if boot firmware now owns EHCI, spin till
+			 * it hands it over.
+			 */
+			msec = 5000;
+			while ((cap & EHCI_USBLEGSUP_BIOS) && (msec > 0)) {
+				msleep(10);
+				msec -= 10;
+				pci_read_config_dword(pdev, offset, &cap);
+			}
+
+			if (cap & EHCI_USBLEGSUP_BIOS) {
+				/* well, possibly buggy BIOS... try to shut
+				 * it down, and hope nothing goes too wrong
 				 */
-				printk(KERN_WARNING "%s %s: early BIOS handoff "
+				printk(KERN_WARNING "%s %s: BIOS handoff "
 						"failed (BIOS bug ?)\n",
 					pdev->dev.bus_id, "EHCI");
-				pci_write_config_dword(pdev,
-						hcc_params + EHCI_USBLEGSUP,
-						EHCI_USBLEGSUP_OS);
-				pci_write_config_dword(pdev,
-						hcc_params + EHCI_USBLEGCTLSTS,
-						0);
+				pci_write_config_byte(pdev, offset + 2, 0);
 			}
+
+			/* just in case, always disable EHCI SMIs */
+			pci_write_config_dword(pdev,
+					offset + EHCI_USBLEGCTLSTS,
+					0);
+			break;
+		case 0:			/* illegal reserved capability */
+			cap = 0;
+			/* FALLTHROUGH */
+		default:
+			printk(KERN_WARNING "%s %s: unrecognized "
+					"capability %02x\n",
+					pdev->dev.bus_id, "EHCI",
+					cap & 0xff);
+			break;
 		}
+		offset = (cap >> 8) & 0xff;
 	}
+	if (!count)
+		printk(KERN_DEBUG "%s %s: capability loop?\n",
+				pdev->dev.bus_id, "EHCI");
 
 	/*
 	 * halt EHCI & disable its interrupts in any case