On Fri, Nov 19, 2010 at 05:14:15PM +0100, ext Derrick, David wrote: > >-----Original Message----- > >From: Jean Pihet [mailto:jean.pihet@xxxxxxxxxxxxxx] > >Sent: Friday, November 19, 2010 9:37 AM > > >On Thu, Nov 18, 2010 at 7:34 PM, Jean Pihet <jean.pihet@xxxxxxxxxxxxxx> >wrote: > >> On Thu, Nov 18, 2010 at 7:27 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: > >>> * Jean Pihet <jean.pihet@xxxxxxxxxxxxxx> [101118 10:06]: > >>>> On Thu, Nov 18, 2010 at 6:52 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: > >>>> > >>>> About the DPLL lock: > >>>> 1) wait_sdrc_ok is only called when back from the non-OFF modes, > >>>> 2) I checked that when running wait_sdrc_ok the CORE is already out of > >>>> idle and the DPLL is already locked. Note: l-o code has no support for > >>>> the voltages OFF and the external clocks OFF. > >>>> > >>>> What to conclude from 1) and 2)? In my test setup ot looks like > >>>> wait_sdrc_ok is of no use, but I agree this a premature conclusion. > >>> > >>> Yeah we should figure out in which cases wait_sdrc_ok is needed. > >>> > >>> BTW, are you sure you're hitting core idle in your tests? > >> Yes it is OK from the console messages and the counters values in > >> /debug/pm_debug/count. > >> > >> Let me confirm asap with the PRCM registers dump. > > >Here is what I experimented: > >1) added a cache flush (v7_flush_kern_cache_all) just before WFI, in all >cases, > >2) checked the real state entered in low power mode from the console > >messages, the output of /debug/pm_debug/count and PRCM registers dump > > >2) is OK, which means that the RET and OFF modes are correctly hit. > > >Can I conclude from 1) that the wake-up code is not running from the > >cache in RETention? > > [Derrick, David] > > To add some context to the wait_sdrc_ok function and why it was added: > > wait_sdrc_ok was added because the DLL takes 500 L3 clock cycles > to lock. So you do not want to go back to DDR before DLL is locked. Also, we > found some times DLL never locked so we introduced the DLL kick procedure to > force it to lock. > The root cause for the DLL not locking has been found though and a workaround implemented. So it should work now :) That still leaves the 500 L3 cycle delay though. Cheers, Peter. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
