patch "ehci: fix EHCI host controller initialization sequence" added to usb-linus

This is a note to let you know that I've just added the patch titled

ehci: fix EHCI host controller initialization sequence

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 280a9045bb18833db921b316a5527d2b565e9f2e Mon Sep 17 00:00:00 2001
From: Eugene Korenevsky <[email protected]>
Date: Sun, 10 Jan 2021 20:36:09 +0300
Subject: ehci: fix EHCI host controller initialization sequence

According to EHCI spec, EHCI HC clears USBSTS.HCHalted whenever USBCMD.RS=1.

However, it is a good practice to wait some time after setting USBCMD.RS (approximately 100ms) until USBSTS.HCHalted become zero.

Without this waiting, VirtualBox's EHCI virtual HC accidentally hangs (see BugLink).

---
 drivers/usb/host/ehci-hcd.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

index e358ae17d51e..1926b328b6aa 100644
@@ -574,6 +574,7 @@ static int ehci_run (struct usb_hcd *hcd)
 	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
 	u32			temp;
 	u32			hcc_params;
+	int			rc;
 
 	hcd->uses_new_polling = 1;
 

@@ -629,9 +630,20 @@ static int ehci_run (struct usb_hcd *hcd)
 	down_write(&ehci_cf_port_reset_rwsem);
 	ehci->rh_state = EHCI_RH_RUNNING;
 	ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag);
+
+	/* Wait until HC become operational */
 	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted writes */
 	msleep(5);
+	rc = ehci_handshake(ehci, &ehci->regs->status, STS_HALT, 0, 100 * 1000);
+
 	up_write(&ehci_cf_port_reset_rwsem);
+
+	if (rc) {
+		ehci_err(ehci, "USB %x.%x, controller refused to start: %d\n",
+			 ((ehci->sbrn & 0xf0)>>4), (ehci->sbrn & 0x0f), rc);
+		return rc;
+	}
+
 	ehci->last_periodic_enable = ktime_get_real();
 
 	temp = HC_VERSION(ehci, ehci_readl(ehci, &ehci->caps->hc_capbase));

2.30.0