On Tue, Sep 27, 2011 at 10:39:44AM -0600, Julian Elischer wrote: > On 9/27/11 4:12 AM, Gavin Atkinson wrote: > >On Mon, 2011-09-26 at 09:30 -0400, John Baldwin wrote: > >>On Friday, September 23, 2011 11:21:06 am Gavin Atkinson wrote: > >>>On Thu, 2011-09-22 at 20:07 +0200, Hans Petter Selasky wrote: > >>>>On Thursday 22 September 2011 19:55:23 David Somayajulu wrote: > >>>>>It appears that the pause() function cannot be used in driver functions > >>>>>which are invoked early in the boot process. Is there is a kernel api > >>>>>which a device driver can use to determine whether to use pause() or > >>>>>DELAY(), for delays which are say greater than 10hz - may be even 1 hz > >>>>>? > >>>>Maybe you want to use something like this: > >>>> > >>>>if (cold) > >>>> DELAY() > >>>>else > >>>> pause() > >>>> > >>>>In your code. > >>>Note that this still shouldn't be done in your suspend/resume paths, as > >>>"cold" isn't set there, however there also appears to be no guarantee > >>>that pause() will ever return (as you could be running after the timer > >>>has been suspended, or before it resumes). > >>> > >>>I'm not sure what the correct answer is for suspend/resume code. > >>Hmmm, on x86 the timers are explicitly shutdown after the DEVICE_SUSPEND() > >>pass over the tree and re-enabled before DEVICE_RESUME(). Perhaps this > >>has > >>changed in HEAD though with the eventtimers stuff. I do think it is best > >>however, to use DELAY() in the suspend/resume path always regardless. > >I don't think head is any different from stable/8 in this respect - the > >same hack patch that fixes suspend/resume for me on head also fixes it > >on stable/8 (the patch basically fakes "cold" during USB > >suspend/resume). See my email to -usb a few months ago: > >http://docs.FreeBSD.org/cgi/mid.cgi?alpine.LNX.2.00.1106041548370.26975 > > > >I'd really like some guidance as to the correct solution to this, I have > >four separate laptops which fail out of the box on 8 and 9, but > >suspend/resume perfectly with this hack. > > code for timers should have a generally readable state that says if > they are useable or not, and we should test that instead of 'cold'
I think that this should be encapsulated into the usable function, instead of being directly exposed to the driver authors. With the my lack of imagination, I propose driver_delay() that would do if (cold) ... inside.
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