> -----Original Message----- > From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > Sent: Thursday, August 26, 2021 11:28 PM > To: Neal Liu <neal_liu@xxxxxxxxxxxxxx> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Tony Prisk > <linux@xxxxxxxxxxxxxxx>; linux-usb@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; Tao Ren > <rentao.bupt@xxxxxxxxx>; BMC-SW <BMC-SW@xxxxxxxxxxxxxx> > Subject: Re: [PATCH] usb: host: ehci: skip STS_HALT check for aspeed platform > > On Thu, Aug 26, 2021 at 03:15:25PM +0800, neal_liu wrote: > > STS_HALT also depends on ASS/PSS status for apseed. > > Skip this check on startup. > > > > Signed-off-by: neal_liu <neal_liu@xxxxxxxxxxxxxx> > > --- > > drivers/usb/host/ehci-hcd.c | 10 +++++++++- > > drivers/usb/host/ehci-platform.c | 6 ++++++ > > drivers/usb/host/ehci.h | 1 + > > 3 files changed, 16 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c > > index 10b0365f3439..a539e11502ef 100644 > > --- a/drivers/usb/host/ehci-hcd.c > > +++ b/drivers/usb/host/ehci-hcd.c > > @@ -634,7 +634,15 @@ static int ehci_run (struct usb_hcd *hcd) > > /* 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); > > + > > + /* For Aspeed, STS_HALT also depends on ASS/PSS status. > > + * Skip this check on startup. > > + */ > > + if (ehci->is_aspeed) > > + rc = 0; > > + else > > + rc = ehci_handshake(ehci, &ehci->regs->status, STS_HALT, > > + 0, 100 * 1000); > > You must not do this. You are assuming the controller will always begin > operating within 5 ms of the time it is told to start. What happens if you are > wrong? > > There must be some way for the aspeed controller's host computer to tell > when the controller has started running. Find out what it is and use it. > > Alan Stern We can check the command RS bit to tell the controller has started running. I'll sent next patch within this change. Thanks -Neal Liu
