linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Chunfeng Yun <chunfeng.yun@mediatek.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alan Stern <stern@rowland.harvard.edu>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	Nishad Kamdar <nishadkamdar@gmail.com>,
	<linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>,
	Eddie Hung <eddie.hung@mediatek.com>
Subject: [PATCH v2] usb: core: reduce power-on-good delay time of root hub
Date: Sat, 10 Apr 2021 09:20:45 +0800	[thread overview]
Message-ID: <1618017645-12259-1-git-send-email-chunfeng.yun@mediatek.com> (raw)

Return the exactly delay time given by root hub descriptor,
this helps to reduce resume time etc.

Due to the root hub descriptor is usually provided by the host
controller driver, if there is compatibility for a root hub,
we can fix it easily without affect other root hub

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
v2: remove RFC tag, and add acked-by Alan
---
 drivers/usb/core/hub.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 73f4482d833a..22ea1f4f2d66 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -148,8 +148,10 @@ static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)
 {
 	unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;
 
-	/* Wait at least 100 msec for power to become stable */
-	return max(delay, 100U);
+	if (!hub->hdev->parent)	/* root hub */
+		return delay;
+	else /* Wait at least 100 msec for power to become stable */
+		return max(delay, 100U);
 }
 
 static inline int hub_port_debounce_be_connected(struct usb_hub *hub,
-- 
2.18.0


             reply	other threads:[~2021-04-10  1:21 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-10  1:20 Chunfeng Yun [this message]
2021-11-01  3:33 ` Walt Jr. Brake
     [not found] ` <5e907ccd-40bb-2ece-fe05-1a65a74f3aa2@gmail.com>
2021-11-01 14:06   ` Alan Stern
2021-11-02  9:05     ` Mathias Nyman
2021-11-02 20:29       ` Walt Jr. Brake
2021-11-03 20:37         ` Mathias Nyman
2021-11-05 10:00           ` Greg Kroah-Hartman
2021-11-05 13:30             ` Alan Stern
2021-11-05 16:00               ` [PATCH] xhci: Fix USB 3.1 enumeration issues by increasing roothub power-on-good delay Mathias Nyman
2021-11-05 16:09                 ` Mathias Nyman
2021-11-05 17:32                   ` Walt Jr. Brake
2021-11-05 19:41                     ` Mathias Nyman
2021-11-05 16:15                 ` Greg KH
2021-11-05 19:56                   ` Mathias Nyman
2021-11-06 14:41                     ` Greg KH

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=1618017645-12259-1-git-send-email-chunfeng.yun@mediatek.com \
    --to=chunfeng.yun@mediatek.com \
    --cc=eddie.hung@mediatek.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mediatek@lists.infradead.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=matthias.bgg@gmail.com \
    --cc=nishadkamdar@gmail.com \
    --cc=stern@rowland.harvard.edu \
    --subject='Re: [PATCH v2] usb: core: reduce power-on-good delay time of root hub' \
    /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).