LKML Archive on
 help / color / Atom feed
From: Douglas Anderson <>
To: John Youn <>
Cc: "Yunzhi Li" <>,
	"Heiko Stübner" <>,,
	"Julius Werner" <>,
	"Douglas Anderson" <>,,,,
Subject: [PATCH 5/5] usb: dwc2: reduce dwc2 driver probe time
Date: Wed,  7 Oct 2015 17:48:41 -0700
Message-ID: <> (raw)
In-Reply-To: <>

From: Yunzhi Li <>

I found that the probe function of dwc2 driver takes much time
when kernel boot up. There are many long delays in the probe
function these take almost 1 second.

This patch trying to reduce unnecessary delay time.

In dwc2_core_reset() I see it use two at least 20ms delays to
wait AHB idle and core soft reset, but dwc2 data book said that
dwc2 core soft reset and AHB idle just need a few clocks (I think
it refers to AHB clock, and AHB clock run at 150MHz in my RK3288
board), so 20ms is too long, delay 1us for wait AHB idle and soft
reset is enough.

And in dwc2_get_hwparams() it takes 150ms to wait ForceHostMode
and ForceDeviceMode valid but in data book it said software must
wait at least 25ms before the change to take effect, so I reduce
this time to 25ms~50ms. By the way, is there any state bit show
that the force mode take effect ? Could we poll curmod bit for
figuring out if the change take effect ?

It seems that usleep_range() at boot time will pick the longest
value in the range. In dwc2_core_reset() there is a very long
delay takes 200ms, and this function run twice when probe, could
any one tell me is this delay time resonable ?

I have tried this patch in my RK3288-evb board. It works well.

Signed-off-by: Yunzhi Li <>
Signed-off-by: Douglas Anderson <>
 drivers/usb/dwc2/core.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index 27ade0c..59fe48f 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -491,7 +491,7 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg)
 	/* Wait for AHB master IDLE state */
 	do {
-		usleep_range(20000, 40000);
+		udelay(1);
 		greset = dwc2_readl(hsotg->regs + GRSTCTL);
 		if (++count > 50) {
@@ -506,7 +506,7 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg)
 	greset |= GRSTCTL_CSFTRST;
 	dwc2_writel(greset, hsotg->regs + GRSTCTL);
 	do {
-		usleep_range(20000, 40000);
+		udelay(1);
 		greset = dwc2_readl(hsotg->regs + GRSTCTL);
 		if (++count > 50) {
@@ -537,7 +537,7 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg)
 	 * NOTE: This long sleep is _very_ important, otherwise the core will
 	 * not stay in host mode after a connector ID change!
-	usleep_range(150000, 200000);
+	usleep_range(150000, 160000);
 	return 0;
@@ -3107,7 +3107,7 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 		gusbcfg = dwc2_readl(hsotg->regs + GUSBCFG);
 		dwc2_writel(gusbcfg | GUSBCFG_FORCEHOSTMODE,
 			    hsotg->regs + GUSBCFG);
-		usleep_range(100000, 150000);
+		usleep_range(25000, 50000);
 	gnptxfsiz = dwc2_readl(hsotg->regs + GNPTXFSIZ);
@@ -3116,7 +3116,7 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 	dev_dbg(hsotg->dev, "hptxfsiz=%08x\n", hptxfsiz);
 	if (hsotg->dr_mode != USB_DR_MODE_HOST) {
 		dwc2_writel(gusbcfg, hsotg->regs + GUSBCFG);
-		usleep_range(100000, 150000);
+		usleep_range(25000, 50000);
 	/* hwcfg2 */

      parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-08  0:48 [PATCH 0/5] usb: dwc2: fix dwc2_get_hwparams() + optimize probe time a bit Douglas Anderson
2015-10-08  0:48 ` [PATCH 1/5] usb: dwc2: Restore GUSBCFG in dwc2_get_hwparams() Douglas Anderson
2015-10-08  0:48 ` [PATCH 2/5] usb: dwc2: reset dwc2 core before dwc2_get_hwparams() Douglas Anderson
2015-10-08  0:48 ` [PATCH 3/5] CHROMIUM: usb: dwc2: Avoid double-reset at boot time Douglas Anderson
2015-10-08 17:34   ` Doug Anderson
2015-10-08  0:48 ` [PATCH 4/5] usb: dwc2: Speed dwc2_get_hwparams() on some host-only ports Douglas Anderson
2015-10-08  0:48 ` Douglas Anderson [this message]

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:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on

Archives are clonable:
	git clone --mirror lkml/git/0.git
	git clone --mirror lkml/git/1.git
	git clone --mirror lkml/git/2.git
	git clone --mirror lkml/git/3.git
	git clone --mirror lkml/git/4.git
	git clone --mirror lkml/git/5.git
	git clone --mirror lkml/git/6.git
	git clone --mirror lkml/git/7.git
	git clone --mirror lkml/git/8.git
	git clone --mirror lkml/git/9.git
	git clone --mirror lkml/git/10.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ \
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone