LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: mathias.nyman@intel.com, gregkh@linuxfoundation.org,
	stern@rowland.harvard.edu
Cc: acelan.kao@canonical.com, linux-usb@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Kai-Heng Feng <kai.heng.feng@canonical.com>
Subject: [RESEND] [PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3
Date: Wed,  5 Feb 2020 19:26:31 +0800	[thread overview]
Message-ID: <20200205112633.25995-1-kai.heng.feng@canonical.com> (raw)

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.

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>
---
v2:
 - Remove some redundant debug messages.
 - Use msleep loop outside if spinlock to stop pegging CPU.

 drivers/usb/host/xhci-hub.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 7a3a29e5e9d2..d3c5bcf76755 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1313,7 +1313,16 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			xhci_set_link_state(xhci, ports[wIndex], link_state);
 
 			spin_unlock_irqrestore(&xhci->lock, flags);
-			msleep(20); /* wait device to enter */
+			if (link_state == USB_SS_PORT_LS_U3) {
+				int retries = 10;
+
+				while (retries--) {
+					msleep(10); /* wait device to enter */
+					temp = readl(ports[wIndex]->addr);
+					if ((temp & PORT_PLS_MASK) == XDEV_U3)
+						break;
+				}
+			}
 			spin_lock_irqsave(&xhci->lock, flags);
 
 			temp = readl(ports[wIndex]->addr);
-- 
2.17.1


             reply	other threads:[~2020-02-05 11:42 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05 11:26 Kai-Heng Feng [this message]
2020-02-05 11:26 ` [RESEND] [PATCH v2 2/3] xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0 Kai-Heng Feng
2020-02-10 14:31   ` Mathias Nyman
2020-02-05 11:26 ` [RESEND] [PATCH v2 3/3] USB: Disable LPM on WD19's Realtek Hub Kai-Heng Feng
2020-03-11  3:32   ` Kai-Heng Feng
2020-03-11 14:15     ` Alan Stern

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=20200205112633.25995-1-kai.heng.feng@canonical.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=stern@rowland.harvard.edu \
    --subject='Re: [RESEND] [PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3' \
    /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

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).