From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Mathias Nyman <mathias.nyman@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alan Stern <stern@rowland.harvard.edu>,
AceLan Kao <acelan.kao@canonical.com>,
USB list <linux-usb@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3
Date: Mon, 13 Jan 2020 17:10:02 +0800 [thread overview]
Message-ID: <CAAd53p5a2RFpZuHGvuNO_9kgv4dGhHCYU0jeq44FtKJv0Ky8uA@mail.gmail.com> (raw)
In-Reply-To: <607e395f-21ce-3c9f-eff7-2fa6aaa74595@linux.intel.com>
On Fri, Jan 10, 2020 at 5:33 PM Mathias Nyman
<mathias.nyman@linux.intel.com> wrote:
>
> On 3.1.2020 10.40, Kai-Heng Feng wrote:
> > The xHCI spec doesn't specify the upper bound of U3 transition time. For
> > some devices 20ms is not enough, so we need to make sure the link state
> > is in U3 before further actions.
>
> Looking at the USB 3.2 spec (7.2.4.2 Link Power management and Flow) it seems
> most timers related to U3 entry are a lot less than a millisecond (4-16us)
> If port is in U1/U2, Ux_EXIT_TIMER is 6ms which seems to be the longest timeout.
>
> If we anyway are polling for the U3 state we could shorten the initial 20ms sleep
> down to 10ms. I think many devices, especially if they are already in U0
> could manage this.
Ok.
>
> are >
> > I've tried to use U3 Entry Capability by setting U3 Entry Enable in
> > config register, however the port change event for U3 transition
> > interrupts the system suspend process.
> >
> > For now let's use the less ideal method by polling PLS.
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> > ---
> > drivers/usb/host/xhci-hub.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> > index 7a3a29e5e9d2..2b2e9d004dbf 100644
> > --- a/drivers/usb/host/xhci-hub.c
> > +++ b/drivers/usb/host/xhci-hub.c
> > @@ -1228,6 +1228,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> > break;
> > case USB_PORT_FEAT_LINK_STATE:
> > temp = readl(ports[wIndex]->addr);
> > + xhci_dbg(xhci, "before setting link state, actual port %d-%d status = 0x%0x\n", hcd->self.busnum, wIndex + 1, temp);
>
> xhci_set_link_state() already shows similar debugging,
Ok, will remove it.
>
> > /* Disable port */
> > if (link_state == USB_SS_PORT_LS_SS_DISABLED) {
> > xhci_dbg(xhci, "Disable port %d\n", wIndex);
> > @@ -1316,9 +1317,17 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> > msleep(20); /* wait device to enter */
> > spin_lock_irqsave(&xhci->lock, flags);
> >
> > - temp = readl(ports[wIndex]->addr);
> > - if (link_state == USB_SS_PORT_LS_U3)
> > + if (link_state == USB_SS_PORT_LS_U3) {
> > + retval = xhci_handshake(ports[wIndex]->addr, PORT_PLS_MASK, XDEV_U3, 80 * 1000);
> > + if (retval)
> > + xhci_dbg(xhci, "polling XDEV_U3 on port %d-%d timeout\n", hcd->self.busnum, wIndex + 1);
>
> In worst case we are busylooping for 80ms here, keeping the cpu busy.
> It should be ok to sleep here, so how about just reading the register
> every 10ms max 10 times, sleeping in between.
Ok. Is the polling safe outside of spin_lock_irqsave()?
Kai-Heng
>
> -Mathias
next prev parent reply other threads:[~2020-01-13 9:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-03 8:40 [PATCH 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3 Kai-Heng Feng
2020-01-03 8:40 ` [PATCH 2/3] xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0 Kai-Heng Feng
2020-01-10 15:29 ` Mathias Nyman
2020-01-13 9:18 ` Kai-Heng Feng
2020-01-14 14:48 ` Mathias Nyman
2020-01-03 8:40 ` [PATCH 3/3] USB: Disable LPM on WD19's Realtek Hub during setting its ports to U0 Kai-Heng Feng
2020-01-03 15:21 ` Alan Stern
2020-01-03 16:25 ` Kai-Heng Feng
2020-01-03 16:54 ` Alan Stern
2020-01-04 6:41 ` Kai-Heng Feng
2020-01-04 16:20 ` Alan Stern
2020-01-06 6:19 ` Kai-Heng Feng
2020-01-06 15:08 ` Alan Stern
2020-01-10 7:35 ` Kai-Heng Feng
2020-01-10 8:02 ` [PATCH v2 3/3] USB: Disable LPM on WD19's Realtek Hub Kai-Heng Feng
2020-01-10 15:40 ` Alan Stern
2020-01-10 15:51 ` Kai-Heng Feng
2020-01-10 16:36 ` Alan Stern
2020-01-10 16:46 ` Kai-Heng Feng
2020-01-11 19:23 ` Greg KH
2020-01-13 9:06 ` Kai-Heng Feng
2020-01-10 9:34 ` [PATCH 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3 Mathias Nyman
2020-01-13 9:10 ` Kai-Heng Feng [this message]
2020-01-14 15:07 ` Mathias Nyman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAAd53p5a2RFpZuHGvuNO_9kgv4dGhHCYU0jeq44FtKJv0Ky8uA@mail.gmail.com \
--to=kai.heng.feng@canonical.com \
--cc=acelan.kao@canonical.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=mathias.nyman@intel.com \
--cc=mathias.nyman@linux.intel.com \
--cc=stern@rowland.harvard.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).