Re: Choosing between DELAY(useconds) and pause()
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. pgp30errILlUx.pgp Description: PGP signature
Re: Choosing between DELAY(useconds) and pause()
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' Thanks, Gavin ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org" ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
Re: Choosing between DELAY(useconds) and pause()
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. Thanks, Gavin ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
Re: Choosing between DELAY(useconds) and pause()
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. -- John Baldwin ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
Re: Choosing between DELAY(useconds) and pause()
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. Gavin ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
Re: Choosing between DELAY(useconds) and pause()
if (cold) DELAY() else pause() On Sep 22, 2011, at 11:55 AM, 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 ? > > Cheers, > David S. > > > > This message and any attached documents contain information from QLogic > Corporation or its wholly-owned subsidiaries that may be confidential. If you > are not the intended recipient, you may not read, copy, distribute, or use > this information. If you have received this transmission in error, please > notify the sender immediately by reply e-mail and then delete this message. > ___ > freebsd-driv...@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-drivers > To unsubscribe, send any mail to "freebsd-drivers-unsubscr...@freebsd.org" > > ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
Re: Choosing between DELAY(useconds) and pause()
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. --HPS ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
