USB enumeration timeout?
in [Device Drivers]
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From: Pavel A. on 18 Nov 2009 06:02 "Hannes" <hannes.news(a)newsgroup.nospam> wrote in message news:56706333-1D83-4760-A3EE-05237C0AA07D(a)microsoft.com... > Hi, > > This could be very alarming for us and our products. > > Our device currently takes a few seconds from power-on to start up its USB > stack. > Is the requirement really <500ms, i.e. is our device is completely > unacceptable? > > / Hannes. All devices belong to either of two kinds: compatible with Windows and not compatible. Your device is "alternatively compatible" as they say in the USA :) --pa
From: Leo Havmøller on 18 Nov 2009 07:09 "Hannes" <hannes.news(a)newsgroup.nospam> wrote in message news:56706333-1D83-4760-A3EE-05237C0AA07D(a)microsoft.com... > Hi, > > This could be very alarming for us and our products. > > Our device currently takes a few seconds from power-on to start up its USB > stack. > Is the requirement really <500ms, i.e. is our device is completely > unacceptable? The timing requirements start when you attach to the bus. Your device may take as long as it wants to startup and then attach when your USB stack is ready. Leo Havmøller
From: Pavel A. on 18 Nov 2009 07:30 "Leo Havm�ller" <rtxleh(a)nospam.nospam> wrote in message news:B0AA57FA-F579-42F8-BC5E-FA9A71BFCF88(a)microsoft.com... > The timing requirements start when you attach to the bus. > Your device may take as long as it wants to startup and then attach when > your USB stack is ready. > > Leo Havmøller No, this is a much worse scenario: resume. The device has been attached before standby. The intent is that it won't disappear after resume. --pa
From: Hannes on 18 Nov 2009 09:09 Exactly, Pavel. Thanks! Our device was attached and with drivers loaded, before sleep. Then, after resume, our drivers get unloaded because we take too long to attach to the bus. So - how long can we wait, max, from resume power-on, to attaching to the USB bus, in order for our drivers NOT to get unloaded? 1sec? 2secs? 1.5secs? (I guess this might also be covered as part of Velocity testing.) / Hannes.
From: Leo Havmøller on 18 Nov 2009 09:22
"Hannes" <hannes.news(a)newsgroup.nospam> wrote in message news:58352B8D-DC71-474A-9CED-BCC3D9E752DD(a)microsoft.com... > Exactly, Pavel. Thanks! > Our device was attached and with drivers loaded, before sleep. > Then, after resume, our drivers get unloaded because we take too long to > attach to the bus. In that case you are already attached to be bus, and the requirements are much stricter. The USB specs require the following for suspend/resume: - Device must be in low-power state (max draw 2.5 mA) maximum 7 ms after suspend is ordered. - Device must be able to respond after resume has been signalled - and resume is 10 ms long. Leo Havmøller. |