* Re: Duration of mdelay and udelay depends on MPU frequency in SMP [not found] ` <4DCB8158.8060507@ti.com> @ 2011-06-10 22:19 ` Menon, Nishanth 2011-06-14 3:24 ` Stephen Boyd 0 siblings, 1 reply; 3+ messages in thread From: Menon, Nishanth @ 2011-06-10 22:19 UTC (permalink / raw) To: Santosh Shilimkar; +Cc: Saquib, linux-arm-kernel, linux-omap On Thu, May 12, 2011 at 01:42, Santosh Shilimkar <santosh.shilimkar@ti.com> wrote: > On 5/5/2011 12:23 PM, Saquib wrote: >> Can anyone please help me to understand and fix this issue? >> >> When CPU frequency is "1008MHz", duration of delay was close to >> theoretical value, however, when "300MHz", it was close to about 4 times >> the theoretical value. >> >> I tested it on OMAP4(SMP) blaze board. > >> > It's a well known problem if the udelay() is based of global lpj. > You can read more here [1] > > Regards > Santosh > [1] http://eeek.borgchat.net/lists/arm-kernel/msg120702.html I am curious about this topic now. Searching Russel's patchworks for this: http://www.arm.linux.org.uk/developer/patches/search.php?summary=udelay I see nothing queued. What is the recommendation for udelay? Regards, Nishanth Menon ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Duration of mdelay and udelay depends on MPU frequency in SMP 2011-06-10 22:19 ` Duration of mdelay and udelay depends on MPU frequency in SMP Menon, Nishanth @ 2011-06-14 3:24 ` Stephen Boyd 2011-06-14 4:19 ` Menon, Nishanth 0 siblings, 1 reply; 3+ messages in thread From: Stephen Boyd @ 2011-06-14 3:24 UTC (permalink / raw) To: Menon, Nishanth Cc: Santosh Shilimkar, Saquib, linux-omap, linux-arm-kernel@lists.infradead.org, Russell King - ARM Linux On 06/10/2011 03:19 PM, Menon, Nishanth wrote: > On Thu, May 12, 2011 at 01:42, Santosh Shilimkar > <santosh.shilimkar@ti.com> wrote: >> >> It's a well known problem if the udelay() is based of global lpj. >> You can read more here [1] >> >> Regards >> Santosh >> [1] http://eeek.borgchat.net/lists/arm-kernel/msg120702.html > I am curious about this topic now. > Searching Russel's patchworks for this: > http://www.arm.linux.org.uk/developer/patches/search.php?summary=udelay > I see nothing queued. What is the recommendation for udelay? The patches are sitting in Russell's patch tracker, waiting for him to accept/reject them. http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6874/1 http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6875/1 http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6873/1 -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Duration of mdelay and udelay depends on MPU frequency in SMP 2011-06-14 3:24 ` Stephen Boyd @ 2011-06-14 4:19 ` Menon, Nishanth 0 siblings, 0 replies; 3+ messages in thread From: Menon, Nishanth @ 2011-06-14 4:19 UTC (permalink / raw) To: Stephen Boyd Cc: Santosh Shilimkar, Saquib, linux-omap, linux-arm-kernel@lists.infradead.org, Russell King - ARM Linux On Mon, Jun 13, 2011 at 22:24, Stephen Boyd <sboyd@codeaurora.org> wrote: > On 06/10/2011 03:19 PM, Menon, Nishanth wrote: >> On Thu, May 12, 2011 at 01:42, Santosh Shilimkar >> <santosh.shilimkar@ti.com> wrote: >>> >>> It's a well known problem if the udelay() is based of global lpj. >>> You can read more here [1] >>> >>> Regards >>> Santosh >>> [1] http://eeek.borgchat.net/lists/arm-kernel/msg120702.html >> I am curious about this topic now. >> Searching Russel's patchworks for this: >> http://www.arm.linux.org.uk/developer/patches/search.php?summary=udelay >> I see nothing queued. What is the recommendation for udelay? > > The patches are sitting in Russell's patch tracker, waiting for him to > accept/reject them. > > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6874/1 > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6875/1 > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6873/1 thanks for the same and hope these do get through :) Regards, Nishanth Menon ^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-06-10 22:19 ` Duration of mdelay and udelay depends on MPU frequency in SMP Menon, Nishanth
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