#9054 HIGH 9.1.0: Speed up USB resume.

[Zarro Boogs per Child]

#9054: Speed up USB resume.
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           Reporter:  cjb     |       Owner:  dsaxena      
               Type:  defect  |      Status:  assigned     
           Priority:  high    |   Milestone:  9.1.0        
          Component:  kernel  |     Version:  not specified
         Resolution:          |    Keywords:  power        
        Next_action:  design  |    Verified:  0            
Deployment_affected:          |   Blockedby:               
           Blocking:          |  
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Comment(by dsaxena):

 I have merged the following patch from 2.6.28 into our master tree. This
 is the patch that Arjan reffered to @ LPC and it only speeds up boot up
 intialization, not resume re-init. Marcelo posted a generic device resume
 parallelization patch but as pointed out in the short thread, there are a
 whole slew of issues in doing parallel resume in a generic way. Next step
 for me is to look at the USB resume path in detail and see where we can
 parallelize.

 {{{
 commit 672cde9409f412e11076e0bac053f1e992748bc4
 Author: Alan Stern <stern at rowland.harvard.edu>
 Date:   Mon Sep 22 14:44:26 2008 -0400

     USB: change hub initialization sleeps to delayed_work

     This patch (as1137) changes the hub_activate() routine, replacing the
     power-power-up and debounce delays with delayed_work calls.  The idea
     is that on systems where the USB stack is compiled into the kernel
     rather than built as modules, these delays will no longer block the
     boot thread.  At least 100 ms is saved for each root hub, which can
     add up to a significant savings in total boot time.

     Arjan van de Ven was very pleased to see that this shaved 700 ms off
     his computer's boot time.  Since his total boot time is on the order
     of two seconds, the improvement is considerable.

     Signed-off-by: Alan Stern <stern at rowland.harvard.edu>
     Tested-by: Arjan van de Ven <arjan at infradead.org>
     Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>

 }}}

-- 
Ticket URL: <http://dev.laptop.org/ticket/9054#comment:5>
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