From: Eugene Korenevsky <ekorenevsky@astralinux.ru>
To: linux-usb@vger.kernel.org
Cc: Alan Stern <stern@rowland.harvard.edu>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH v4] ehci: fix EHCI host controller initialization sequence
Date: Sun, 10 Jan 2021 11:37:07 +0300 [thread overview]
Message-ID: <20210110083707.GA11888@himera.home> (raw)
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).
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=211095
Signed-off-by: Eugene Korenevsky <ekorenevsky@astralinux.ru>
---
drivers/usb/host/ehci-hcd.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index e358ae17d51e..1926b328b6aa 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 +630,20 @@ 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));
--
2.20.1
next reply other threads:[~2021-01-10 8:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-10 8:37 Eugene Korenevsky [this message]
2021-01-10 8:48 ` [PATCH v4] ehci: fix EHCI host controller initialization sequence Greg Kroah-Hartman
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