Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753092AbbGBJlc (ORCPT ); Thu, 2 Jul 2015 05:41:32 -0400 Received: from smtp-out6.electric.net ([192.162.217.195]:54639 "EHLO smtp-out6.electric.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752590AbbGBJlY convert rfc822-to-8bit (ORCPT ); Thu, 2 Jul 2015 05:41:24 -0400 From: David Laight To: "'Peter Chen'" , Mike Looijmans CC: "lars@metafoo.de" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH 1/2] usb: chipidea: Reduce ULPI PHY reset pulse to datasheet spec of 1us Thread-Topic: [PATCH 1/2] usb: chipidea: Reduce ULPI PHY reset pulse to datasheet spec of 1us Thread-Index: AQHQsuLyIYggeXydwkadBjbWnN8DIZ3H697Q Date: Thu, 2 Jul 2015 09:39:28 +0000 Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CB5B140@AcuExch.aculab.com> References: <1435326424-18748-1-git-send-email-mike.looijmans@topic.nl> <20150630020607.GA7586@shlinux2> In-Reply-To: <20150630020607.GA7586@shlinux2> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.202.99.200] Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Outbound-IP: 213.249.233.130 X-Env-From: David.Laight@ACULAB.COM X-PolicySMART: 3396946, 3397078 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1507 Lines: 38 From: Peter Chen > Sent: 30 June 2015 03:06 > On Fri, Jun 26, 2015 at 03:47:03PM +0200, Mike Looijmans wrote: > > The datasheet for the 334x PHY mentions that a reset can be performed: > > "... by bringing the pin low for a minimum of 1 microsecond and > > then high." > > A delay of 5ms to implement that seems overly long, so reduce it to > > just 1us. > > As for the delay after reset, the datasheet only mentioned that the > > chip will assert the DIR output. 1ms seems like a safe time to wait > > for that to happen, so no change there. > > > > Signed-off-by: Mike Looijmans > > --- > > drivers/usb/chipidea/core.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c > > index e970863..c865abe 100644 > > --- a/drivers/usb/chipidea/core.c > > +++ b/drivers/usb/chipidea/core.c > > @@ -664,7 +664,7 @@ static int ci_hdrc_create_ulpi_phy(struct device *dev, struct ci_hdrc *ci) > > dev_err(dev, "Failed to request ULPI reset gpio: %d\n", ret); > > return ret; > > } > > - msleep(5); > > + udelay(1); If the spec says 1us I'd delay for longer just to make sure. And add a comment saying that the reset needs to be 1us long. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/