From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Roese Date: Fri, 11 Mar 2016 07:34:33 +0100 Subject: [U-Boot] [PATCH 2/6] usb: Remove 200 ms delay in usb_hub_port_connect_change() In-Reply-To: <56E1C326.90708@redhat.com> References: <1457625012-1268-1-git-send-email-sr@denx.de> <1457625012-1268-3-git-send-email-sr@denx.de> <56E1C326.90708@redhat.com> Message-ID: <56E266F9.3010208@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 10.03.2016 19:55, Hans de Goede wrote: > Hi, > > On 10-03-16 16:50, Stefan Roese wrote: >> This patch removes 2 mdelay(200) calls from >> usb_hub_port_connect_change(). >> These delays don't seem to be necessary. At least not in my tests. Here >> the number for a custom x86 Bay Trail board (not in mainline yet) with >> a quite large and complex USB hub infrastructure. >> >> Without this patch: >> starting USB... >> USB0: USB EHCI 1.00 >> scanning bus 0 for devices... 9 USB Device(s) found >> >> time: 28.415 seconds >> >> With this patch: >> starting USB... >> USB0: USB EHCI 1.00 >> scanning bus 0 for devices... 9 USB Device(s) found >> >> time: 24.811 seconds >> >> So ~3.5 seconds of USB scanning time reduction. >> >> These mdelay calls are removed if CONFIG_USB_FAST_SCAN is defined. They >> are not removed per default yet. It would be good to test with this >> option enabled on many other boards. And once we have a good testing >> base we can decide to remove these delays completely, including this >> macro. > > There indeed is no reason at all to delay before the reset and the kernel > does not wait with checking the USB_PORT_STAT_SPEED_MASK once the > reset completes, so I see no reason why we should: > > Acked-by: Hans de Goede Thanks. I'll remove the #if !defined(CONFIG_USB_FAST_SCAN) to make this change default in the next patchset version. Thanks, Stefan