From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Date: Fri, 11 Mar 2016 10:53:02 -0700 Subject: [U-Boot] [PATCH v2 0/4] usb: Reduce USB scanning time In-Reply-To: <1457708151-24287-1-git-send-email-sr@denx.de> References: <1457708151-24287-1-git-send-email-sr@denx.de> Message-ID: <56E305FE.8030009@wwwdotorg.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 03/11/2016 07:55 AM, Stefan Roese wrote: > > My current x86 platform (Bay Trail, not in mainline yet) has a quite > complex USB infrastructure with many USB hubs. Here the USB scan takes > an incredible huge amount of time: > > starting USB... > USB0: USB EHCI 1.00 > scanning bus 0 for devices... 9 USB Device(s) found > > time: 28.415 seconds > > This is of course not acceptable on platforms, where USB needs to get > scanned at every bootup. As this increases the bootup time of this > device by nearly 30 seconds! > > This patch series greatly reduces the USB scanning time. This is done > by multiple means: > > - Remove or reduce delays and timeouts > - Remove a 2nd reset of the USB hubs > - Change USB port timeout handling and introduce quasi parallel USB > port scanning > > As a result, the USB scanning time is greatly reduced: > > starting USB... > USB0: USB EHCI 1.00 > scanning bus 0 for devices... 9 USB Device(s) found > > time: 4.606 seconds > > As you can see, the time is reduced from 28.4 to 4.6 seconds! > > Please find more details to the changes in the patch description. > > Testing and comments welcome! The series, Tested-by: Stephen Warren (same set of tests as last time)