According to EHCI spec, EHCI HCD 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.
Instead, previous version of ehci_run() wrote 1 to USBCMD.RS, issued read to
USBCMD and waited for 5 ms.
That worked incorrectly at least at VirtualBox's EHCI virtual HCD and caused
accidental hangs (bugzilla #211095).
This patch fixes #211095.
Signed-off-by: Eugene Korenevsky <ekorenevsky@xxxxxxxxxxxxx>
Tested-by: Eugene Korenevsky <ekorenevsky@xxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index e358ae17d51e..490473af4906 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -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 +630,18 @@ 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);
- ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */
- msleep(5);
+
+ /* Wait until HCD become operational */
+ 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, handshake error: %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));
--
2.20.1
