From: Stephen Warren <swarren@wwwdotorg.org>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 1/2] usb: hub: fix power good delay timing
Date: Thu, 29 May 2014 15:25:32 -0600 [thread overview]
Message-ID: <5387A5CC.60509@wwwdotorg.org> (raw)
In-Reply-To: <1400530878-15956-1-git-send-email-swarren@wwwdotorg.org>
On 05/19/2014 02:21 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren@nvidia.com>
>
> usb_hub_power_on() currently waits for the maximum of (a) the hub port's
> power output to become good, (b) the max time the USB specification
> allows a device to take to connect.
>
> However, these two operations must occur in series rather than in
> parallel. First, the power supply ramps up to the level required to
> power the USB device, and then the device may take a certain amount of
> time to connect (assert D+/D- pullups).
>
> Related, the maximum time that a device has to assert pullups is 1s not
> 100ms.
>
> This is explained in "Connect Timing ECN.pdf", itself part of
> usb_20_042814.zip from www.usb.org.
Marek, does this series look OK?
next prev parent reply other threads:[~2014-05-29 21:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-19 20:21 [U-Boot] [PATCH 1/2] usb: hub: fix power good delay timing Stephen Warren
2014-05-19 20:21 ` [U-Boot] [PATCH 2/2] usb: hub: remove CONFIG_USB_HUB_MIN_POWER_ON_DELAY Stephen Warren
2014-06-03 16:17 ` Tim Harvey
2014-06-03 16:38 ` Stephen Warren
2014-06-03 17:38 ` Marek Vasut
2014-06-03 18:11 ` Tim Harvey
2014-05-29 21:25 ` Stephen Warren [this message]
2014-06-01 17:20 ` [U-Boot] [PATCH 1/2] usb: hub: fix power good delay timing Marek Vasut
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